Communication device, system and method for communication using feedback

ABSTRACT

Communication devices are provided that facilitate receiving information units and providing feedback to other communication devices.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application is a continuation of copending InternationalApplication No. PCT/EP2018/068935, filed Jul. 12, 2018, which isincorporated herein by reference in its entirety, and additionallyclaims priority from European Applications Nos. EP 17 181 315.7, filedJul. 13, 2017, and EP 17 186 157.8, filed Aug. 14, 2017, all of whichare incorporated herein by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to communication devices, for example tocommunication devices that facilitate communication over a broadcastbased communication connection.

Communication between mobile devices in a communication system usuallyinvolves the mobile devices communicating via a base station (BS). Note,the term eNB is a general term for a base station (BS) of thecommunication network and is used in the LTE, LTE-A (4G) and LTE-A Pro(4.5G) context as well as future LTE-based standards. For 5G “New Radio”(NR) communication networks, the term gNB is used as synonym for a basestation. Therefore, all terms BS, eNB and gNB may be used as synonymsthroughout this description. Alternatively, the communication may alsobe performed between the mobile devices directly without involving thebase station as a kind of relay. This kind of communication is alsoreferred to as device-to-device, D2D, or Vehicle-to-everything, V2X,communication and may involve broadcast-based sidelink (SL)communications.

A mobile device is also referred to as user equipment (UE). This termcan refer to all types of mobile devices with different computingcapabilities including mobile phones, laptops, computers with modemcards/functionality, handhelds, tablets, Internet-of-Things (IoT)devices, low power devices, narrowband-IoT devices (NB1, NB2, etc.),communication devices mounted on UAVs (drones, planes, helicopters), orvehicles (e.g. cars, trucks, busses, trains, etc.). The sidelink canalso allow asymmetric computing capabilities, where one device is asmart phone or laptop with high computing powers, and the other node isa low-power IoT device. This link can also support communications amongvehicles. Furthermore, communication nodes may be classified accordingto their power class (in terms of transmit power) or in terms of poweravailability (such as battery power, fixed-power-plugs) and depending onpower capabilities utilized the technology defined below.

Broadcast-based sidelink (SL) communication has been defined without anykind of feedback mechanism, like e.g. HARQ feedback or CQI, and in orderto increase reliability in such a scenario, fixed (re)transmissions ofdata have been specified [1]. However, within the scope FeD2D and V2X,unicast communication between SL devices has been agreed upon in orderto meet the stringent QoS and reliability constraints. Therefore,additional reliability enhancements may include feedback mechanisms toimprove overall performance. According to the RAN1#88bis [8] meeting,there is a desire that no additional channel will be specificallyintroduced for feedback.

It has been found that ‘piggyback’ strategies to convey this feedbackinformation may be desirable.

The D2D based Proximity service (ProSe) communication, which was firststandardized in Release 12 of the 3GPP standard included no feedback andhence no link adaptation mechanism due to the broadcast nature of the SLin this D2D scenario. Similarly, V2X communication has also beendesigned not to include feedback. In order to improve reliability, thesystem would instead consecutively blindly retransmit the broadcasttransport blocks (TBs) in three consecutive subframes on the SL, witheach retransmission having a different redundancy version based on apredefined pattern. In V2X communication, a UE blindly retransmit theTBs in 2 consecutive subframes on the SL. The first retransmissionconfiguration (pattern) is indicated in the Sidelink Control Indicator(SCI) of the first retransmission enabling the receiving user equipment(UE) to demodulate the needed data from all retransmissions [1,7].

The concept of resource pools (RPs) in SL communication is defined as aset of physical resources available to enable D2D and V2Xcommunications. These RPs can comprise of resource blocks and subframes.In the context of SL communication there are a few types of resourcepools:

-   1) PSCCH subframe pool: A set of subframes for PSCCH transmission-   2) PSCCH resource block pool: A set of resource blocks available for    PSCCH transmission within a PSCCH subframe pool.-   3) PSSCH subframe pool: Set of subframes for PSSCH transmissions.-   4) PSSCH resource block pool: Set of available resource blocks for    PSSCH transmissions within a PSSCH subframe pool.

FIG. 31 shows the general structure of the subframe and resource blockpool 3100. It is shown that a part 3110 of the resource block pool isreserved for cellular services, and another part 3120 is reserved forthe proximity service ProSe. In D2D Mode 1, a device's resource poolsare already explicitly assigned by the eNB via a scheduling grant, whilein Mode 2 (distributed scheduling) the device itself selects the set ofPSCCH/PSSCH resources from a subset of resource pools defined in Mode 1.Mode 1 is only for in-coverage UEs in the RRC Connected state, whileMode 2 can be both in the in RRC Idle and RRC Connected state. The TimeRepetition Pattern (TRP) is an indication for the subframes that can beused for PSSCH transmission. The same UE cannot simultaneously utilizethe given subcarrier/subframe for both cellular communications and SLcommunications. In V2X, mode 3 configuration involves the scheduling andinterference management of resources by the base station (BS/eNB/gNB)for vehicular UEs within the coverage of the said BS to enable sidelink(SL) (vehicle-to-vehicle (V2V)) communications. The control signaling isprovided to the UE over the Uu interface (via downlink control indicator(DCI)) and dynamically assigned by the base station. Mode 4configuration for SL communications is autonomously performed usingdistributed (de-centralized) algorithms among UEs based on apreconfigured resource configuration.

TRP's provides an indication of which resources (subframes) are reservedfor SL transmission/reception and does not take into account if theseresources are actually in use. In V2X, the channel busy ratio (CBR)determines the load of the wireless channel (serves as a loadingmetric). A UE can adapt its transmission parameters for each resourcepool based on the CBR and can thus control the channel utilization. Thechannel occupancy ratio (CR) measurement reports the percentage ofmeasurement samples that the RSSI is above a pre-defined threshold,which would indicate occupancy of the particular channel. As itcurrently stands, the channel occupancy ratio is calculated after each(re)-transmission [10].

Retransmission schemes (ACK/NACK) have been proposed in unicast D2D andV2X devices for the in-coverage and the out-of-coverage mode. It hasbeen agreed that there will be no dedicated HARQ feedback channel [3].It has been suggested that basic HARQ feedback be transmitted on thecontrol channel (SCI) of the SL [1,2,4] or part of the schedulingassignment (in autonomous mode) [2]. It has also been proposed that thefeedback be transmitted by puncturing a portion of the PUSCH resourceelements and uplink control indicator (UCI) (when in eNB scheduled mode)[5].

Aspects mentioned above may optionally be combined with the aspects andembodiments of the invention mentioned in the following. Also,definitions mentioned above may optionally be taken over in the aspectsand embodiments of the invention.

In view of the above, there is a desire to create communication conceptwhich provides for an improved tradeoff between reliability, resourceusage and complexity.

SUMMARY

An embodiment may have a communication device, wherein the communicationdevice is configured to receive one or more information units from aplurality of other communication devices, wherein the communicationdevice is configured to receive a resource allocation message from amanaging communication device, wherein the resource allocation messagedefines an allocation of bit positions associated with anacknowledgement of information units received from the plurality ofother communication devices in a combined acknowledgement informationunit; and wherein the communication device is configured to transmit acombined acknowledgement information unit in response to a reception ofinformation units from a plurality of other communication devices usingthe allocation of bit positions defined in the resource allocationmessage.

According to another embodiment, a method for communication may have thesteps of: receiving, at a communication device, one or more informationunits from a plurality of other communication devices, receiving aresource allocation message from a managing communication device,wherein the resource allocation message defines an allocation of bitpositions associated with an acknowledgement of information unitsreceived from the plurality of other communication devices in a combinedacknowledgement information unit; and transmitting a combinedacknowledgement information unit in response to a reception ofinformation units from a plurality of other communication using theallocation of bit positions defined in the resource allocation message.

Another embodiment may have a non-transitory digital storage mediumhaving a computer program stored thereon to perform the method forcommunication, wherein the method has the steps of: receiving, at acommunication device, one or more information units from a plurality ofother communication devices, receiving a resource allocation messagefrom a managing communication device, wherein the resource allocationmessage defines an allocation of bit positions associated with anacknowledgement of information units received from the plurality ofother communication devices in a combined acknowledgement informationunit; and transmitting a combined acknowledgement information unit inresponse to a reception of information units from a plurality of othercommunication using the allocation of bit positions defined in theresource allocation message, when said computer program is run by acomputer.

According to an embodiment, there is provided a communication device,e.g. a so-called receiving communication device, that receives one ormore information units from a second communication device, wherein thecommunication device amends a check value associated with theinformation unit transmitted by the communication device in dependenceon whether an information unit received from the second communicationdevice has been properly received by the communication device or not, tothereby provide a signaling whether the information unit received fromthe second communication device has been properly received or not. Forexample, the communication device may be a mobile communication devicesuch as a user equipment, UE. In examples, the information units may bedata blocks or data packets and/or control blocks or control packets.These information units may have been sent via a direct link, but it isalso possible that the information units have been sent via a sidelink.In examples, the check value may be a cyclic redundancy check, CRC,value, but also any other kind of check values may be used like alongitudinal parity check value, Fletcher's checksum value or the like.The check value may be associated with control information in a PSCCH orwith data in a PSSCH. The information unit transmitted by thecommunication device may be transmitted to a base station, gNB, or toanother user equipment.

This embodiment according to the invention is based on the finding thatit is advantageous to signal whether an information unit has beenproperly received from another (second) communication device byselectively amending a check value of a subsequent transmission, becausethis allows for providing an acknowledgement/non-acknowledgementfeedback without requiring a dedicated resource for the signaling (i.e.for the provision of the acknowledgement/non-acknowledgementinformation). Moreover, it has been found that “modulating” (amending)the check value in dependence on the fact whether a proper reception ofan information unit should be signaled or not does not significantlydegrade the usability of the check value for a detection of an error inan information to which the check value is associated. For example, anumber of possible states or possible values of the check value may besignificantly larger (for example, at least by a factor of 10) than thenumber of states of the acknowledgement information (for example, 2states for a simple acknowledgement or 4 states for a jointacknowledgement of two data units), such that the amendment of the checkvalue does not substantially degrade the usability of the check valuefor error detection. Moreover, the amendment of the check value may becomputationally simple (for example, using a reversible arithmetic orlogical operation), such that another communication device receiving theamended check value can easily detect whether the check value has beenamended (to thereby conclude whether an acknowledgement or anon-acknowledgement is to be signaled) and/or what the original(non-amended) check value has been (to thereby effectively use theamended check value for a detection of a bit error).

To conclude, it has been found that a signaling whether the informationunit received from the second communication device has been properlyreceived or not can be “piggybacked” on a check value computed using a(typically multi-bit) conventional check value computed using aconventional check value computation algorithm (like a CRC algorithm),thereby allowing to transmit the signaling without extra bitrate demandwhile not significantly compromising the usability of the check valueand while keeping complexity reasonably small.

In a further embodiment, the check value allows for a detection of oneor more bit errors within the information unit to which the check valueis associated. For example, the check value may allow detecting biterrors up to a predetermined number of bit errors, and optionally mayalso allow for a correction of these bit errors.

In a further embodiment, the check value is a cyclic redundancy checkvalue.

In a yet further embodiment, the communication device computes the checkvalue on the basis of the information unit to be transmitted using apredetermined computation rule to obtain a computed check value, whereinthe communication device selects a reversible modification rule out of aplurality of reversible modification rules in dependence on whether oneor more information units received from the second communication devicehave been properly received by the communication device or not, whereinthe communication device applies the selected reversible modificationrule to the computed check value in order to obtain the amended checkvalue. For example, the reversible modification rule may be an XOR maskvalue out of a plurality of XOR mask values. In a general, illustrativecase, there may be two states to be signaled, acknowledgement (ACK) ornon-acknowledgement (NACK). However, in examples, there may be morestates, e.g., two code blocks or two code block groups or two HARQprocesses. In an example, if the reception of two information units isto be acknowledged by UE1, a first reversible modification rule, or afirst XOR mask value, may be chosen if both information units have beenproperly received, a second reversible modification rule, or a secondXOR mask value, may be chosen if a first information unit has beenproperly received and a second information unit has not been properlyreceived, a third reversible modification rule or a third XOR mask valuemay be chosen if the first information unit has not been properlyreceived and the second information unit has been properly received, anda fourth reversible modification rule or a fourth XOR mask value may bechosen if both the first and second information units have not beenproperly received. Additionally, one of the reversible modificationrules may leave the check value unchanged what may be equivalent to anXOR with a word/bit-pattern containing only ‘0’ values.

In a further embodiment, the communication device computes the checkvalue on the basis of the information to be transmitted using apredetermined computation rule to obtain a computed check value, whereinthe communication device selectively applies a reversible modificationto the computed check value in dependence of whether the informationunit received from the second communication device has been properlyreceived by the communication device or not, in order to obtain theamended check value, or wherein the communication device selectivelyapplies a first reversible modification or a second reversiblemodification to the computed check value independent of whether theinformation unit received from the second communication device has beenproperly received by the communication device or not, in order to obtainthe amended check value. For example, the predetermined computation rulemay be a generator polynomial. Also in examples, the reversiblemodification may refer to an XOR operation with a predetermined value,for example, the first reversible modification may be an XOR operationwith a first predetermined value in the case a packet received from thesecond communication device has been properly received, or the secondreversible modification may be an XOR operation with a secondpredetermined value in the case a packet received from the secondcommunication device has not been properly received. In a general case,there may be two states, ACK/NACK, however, some embodiments may allowfor more states, e.g., two code blocks or two code block groups or twoHARQ processes, these more than two states may be signaled using morethan two reversible modification operations.

In a further embodiment, the communication device may communicate with abase station and also communicates directly with the secondcommunication device. For example, the base station may be a gNB or aneNB. The base station may be configured to perform a centralizedresource allocation. In examples where the communication device directlycommunicates with the second communication device, the communication isperformed without an involvement of the base station. The secondcommunication device may be different from the base station. Inexamples, this direct communication may be performed using a sidelinkcommunication. This sidelink communication may be, for example,performed by transmitting without a grant, namely grant-free access,using an autonomous scheduling scheme.

In a further embodiment, the communication device receives one or moreinformation units from the second device via a sidelink which does notinvolve a base station. For example, the base station may be a gNB,and/or the receiving may be performed by transmitting without a grantusing an autonomous scheduling scheme.

In a further embodiment, the communication device amends a check valueassociated with a control information unit transmitted by thecommunication device via a control channel in dependence of whether theinformation unit received from the second communication device has beenproperly received by the communication device or not to thereby providea signaling whether the information unit received from the secondcommunication device has been properly received or not, or thecommunication device amends the check value associated with a data unittransmitted by the communication device via a data channel in dependenceof whether the information unit received from the second communicationdevice has been properly received or not, to thereby provide a signalingwhether the packet received from the second communication device hasbeen properly received or not, or wherein the communication deviceamends a check value associated with a control information unittransmitted by the communication device via a control channel and amendsa check value associated with a data unit transmitted by thecommunication device via a data channel in dependence of whether theinformation unit received from the second communication device has beenproperly received by the communication device or not to thereby providea signaling whether the information unit received from the secondcommunication device has been properly received or not. As an example,the check value may be a CRC value or another check value mentionedbefore. The control information unit may be control information in aPhysical Sidelink Control Channel, PSCCH. In examples, the controlinformation unit may have been transmitted to a base station (BS) or tothe second user equipment. In examples, the data unit may be data sentin a Physical Sidelink Shared Channel, PSSCH, and may have beentransmitted to a base station (BS) or to the second user equipment.

In a further embodiment, the communication device transmits theinformation unit, the check value of which is amended in order toprovide a signaling whether the information unit received from thesecond communication device has been properly received or not, to thesecond communication device only via the sidelink which does not involvea base station, or the communication device transmits the informationunit, the check value of which is amended in order to provide asignaling whether the information unit received from the secondcommunication device has been properly received or not to a base stationonly, or the communication device transmits the information unit, thecheck value of which is amended in order to provide a signaling whetherthe information unit received from the second communication device hasbeen properly received or not, to the second communication device via asidelink, which does not involve a base station, and also transmitsanother information unit, the check value of which is amended in orderto provide a signaling whether the information unit received from thesecond communication device has been properly received or not, to a basestation. For example, the information unit may be transmitted to thebase station using an uplink channel.

In an embodiment, the communication device decides whether to transmitthe information unit, the check value of which is amended in order toprovide a signaling whether the information unit received from thesecond communication device has been properly received or not, to thesecond communication device via a sidelink, or whether to transmit saidinformation unit to a base station in dependence on an informationdescribing whether a resource is allocated to the communication devicefor a direct transmission to the second communication device via asidelink which does not involve the base station.

In an embodiment, the communication device computes the check value onthe basis of the information unit to be transmitted using a cyclicredundancy check computation rule to obtain a computed check value, andselectively applies an XOR operation with a predetermined value to thecomputed check value in dependence of whether the information unitreceived from the second communication device has been properly receivedor not, in order to obtain the amended check value, or selectivelyapplies a first XOR operation with a first predetermined value to thecomputed check value in case the information unit received from thesecond communication device has been properly received and selectivelyapplies a second XOR operation with a second predetermined value, whichis different from the first predetermined value, to the computed checkvalue in case the information unit received from the secondcommunication device has not been properly received, in order to obtainthe amended check value. For example, the cyclic redundancy checkcomputation rule may be obtained using a generator polynomial.

According to another embodiment, a communication device, e.g. aso-called sending communication device, is provided that transmits oneor more information units to another communication device and receivesone or more information units having associated one or more check valuesand derives information indicating whether the one or more informationunits transmitted by the communication device have been properlyreceived by another communication device or not, in dependence on theone or more check values. For example, the communication devices may beuser equipments. Also, the information units may be data blocks orpackets and/or control blocks or packets. The communication device maycommunicate with another (i.e. the another) communication devicedirectly via a sidelink without involving the base station, but it isalso possible that the communication device communicates to the basestation. In examples, the check values may be multibit binary values,e.g. CRC values.

This embodiment according to the invention is also based on the findingthat it is advantageous to signal an ACK/NACK condition, which signalswhether an information unit sent by a sending communication device hasbeen properly received by the receiving communication device, using anamended or modified check value of a following transmission, becausethis may help making the communication process more reliable byproviding the mentioned feedback information, and also may savebandwidth because the ACK/NACK information may be piggybacked on thecheck value part of the following transmission, thereby not increasingthe overhead, but double-use the overhead for its original purpose,namely error detection or correction, and for the purpose of providingfeedback. By using a reversible operation that facilitates thesignaling, the check value can still be used with no or no substantiallimitation.

In a further embodiment, the check value may allow for a detection ofone or more bit errors within the information unit to which therespective check value is associated. For example, the check value mayallow for the detection to at least a predetermined number of biterrors, and may also, optionally, allow for a correction of bit errors.

In a further embodiment, the check values are cyclic redundancy check,CRC, values.

In another embodiment, the communication device determines whether theone or more check values correspond with respective information unitsaccording to one out of the plurality of different predeterminedderivation rules or according to one out of a total or fourpredetermined derivation rules or do not correspond with the respectiveinformation units and the communication device derives the informationindicating the one or more information units transmitted by thecommunication device have been properly received by the anothercommunication device or not from a result of said determination. Forexample, the different predetermined derivation rules may comprise twopredetermined derivation rules if, for example, a single ACK/NACK is tobe signaled or may comprise for determined derivation rules, for exampleif two ACKs/NACKs are to be signaled. For example, it may be determinedthat the check values do not correspond with the respective informationunits according to any of the predetermined derivation rules, or evenaccording to one out of a total of more than four predeterminedderivation rules. In general, a feedback information that comprises morethan two states can, for example, be piggybacked using the check value,if more than two different predetermined derivation rules areconsidered, e.g., more than two different values with which the CRCvalue is XOR-ed.

In another embodiment, the communication device determines whether theone or more check values correspond with respective information unitsaccording to a first predetermined derivation rule or according to asecond predetermined derivation rule or do not correspond with therespective information units, and the communication device derives theinformation indicating whether the one or more information unitstransmitted by the communication device have been properly received bythe another communication device or not from a result of saiddetermination. For example, the derivation rule may be a rule forderiving a CRC at another (i.e. the another) communication device incase that a NACK condition is to be signaled. The second predeterminedderivation rule may be a rule for deriving a CRC at anothercommunication device in the case that an ACK condition is to besignaled. It may be determined that the one or more check values do notcorrespond with the respective information units according to any of thepredetermined derivation rules.

In a further embodiment, the communication device performs aretransmission of the one or more transmitted information units inresponse to finding out that the one or more check values do notcorrespond with the respective information units according to apredetermined derivation rule associated with a proper reception.

In another embodiment, the communication device performs aretransmission with an increased robustness when compared to a previoustransmission if the one or more check values do not correspond with therespective information units according to any of the predeterminedderivation rules. For example, the retransmission may be performed witha lower MCS, with higher power or with a repetition coding. It may bedetermined that the one or more check values do not correspond with therespective information units according to neither the derivation rulescorresponding to the signaling of an ACK nor with derivation rulecorresponding with the signaling of a NACK. In different words, if adata packet cannot be correctly corrected, i.e. no CRC mask is matching,a more robust retransmission is sent, e.g., with a lower MCS, higherpower or repetition coding.

In a further embodiment, the communication device retransmits the one ormore information units transmitted to another (i.e. the another)communication device in response to finding that the one or more checkvalues correspond with respective information units according the firstpredetermined derivation rule. For example, the information units may bedata blocks or packets and/or control blocks or packets. Thepredetermined derivation rule may be a rule for deriving a check value,for example, it may be a rule deriving a CRC at the site of anothercommunication device in case that a NACK condition is to be signaled.

In another embodiment, the communication device receives the one or moreinformation units from which the information indicating whether the oneor more information units transmitted by the communication device hasbeen properly received by the another communication device or not isderived from the another communication device to which the communicationdevice has transmitted the one or more data units to be acknowledged,wherein the communication device receives the one or more informationunits from which the information indicating whether the one or moreinformation units transmitted by the communication device have beenproperly received by the another communication device or not from a basestation. For example, the communication device may transmit the one ormore data units via a sidelink without involving a base station. Thebase station may be e.g. a gNB, and the base station may be adapted tocoordinate a resource allocation to the communication devices, andpossibly to other communication devices.

In another embodiment, the communication device derives the informationindicating whether the one or more information units transmitted by thecommunication device have been properly received by the anothercommunication device or not in dependence on the one or more checkvalues associated with the one or more data information units, andwherein the communication device derives the information indicatingwhether the one or more information units transmitted by thecommunication device have been properly received by the anothercommunication device in dependence on the one or more check valuesassociated with the one or more control information units, or whereinthe communication device derives the information indicating whether theone more information units transmitted by the communication device havebeen properly received by the another communication device or not independence on one or more check values associated with one or more datainformation units and in dependence on one or more check valuesassociate with one or more control information units.

In a further embodiment, the communication device computes a check valueon the basis of a given one of the one or more information units using acyclic redundancy check computation rule to obtain a computed checkvalue and wherein the communication device compares the computed checkvalue with a received check value associated with the given one of theone or more information units and checks whether the computed checkvalue is identical with the received check value associated with thegiven one of the one or more information units except for an XORcombination with a predetermined value, and wherein the communicationdevice recognizes a proper reception by the another communication devicein dependence on whether the computed check value is identical with thereceived the check value or whether the computed check value isidentical with the received check value associated with the given one ofthe one or more information units except for an XOR combination with apredetermined value. For example, using a cyclic redundancy checkcomputation rule may comprise using a generator polynomial. Thecommunication device may compare the computed check value with areceived check value by checking for identity. The XOR combination maycomprise the computed check value or the received check value. Thecommunication device may recognize a proper reception of the one or moreinformation units transmitted by the communication device.

In an embodiment, the communication device recognizes a reception errorif the computed check value is different from the received check valueand if the computed check value differs from the received check valueassociated with a given one of the one or more information units by morethan an XOR combination with the predetermined value. For example, thereception error may refer to an error in the reception of an informationunit by the communication device itself. The reception error may berecognized if the computed check value is different from the receivedcheck value and if the computed check value differs from the receivedcheck value also by more than XOR combinations.

In an embodiment, the communication device computes a check value on thebasis of a given one of the one or more information units using cyclicredundancy check computation rule to obtain a computed check value, andthe communication device checks whether the computed check value isidentical with received check value associated with a given one of theone or more information units except for an XOR combination with a firstpredetermined value, and checks whether the computed check value isidentical with the received check value associated with the given one ofthe one or more information units except for an XOR combination with asecond predetermined value, and the communication device recognizes aproper reception by the another communication device independence onwhether the computed check value is identical with the received checkvalue associated with the given one of the one or more information unitsexcept for the XOR combination with the first predetermined value orwhether the computed check value is identical with the received checkvalue associated with the given one of the one or more information unitsexcept for the XOR combination with the second predetermined value. Forexample, using a cyclic redundancy check computation rule may compriseusing a generator polynomial. The XOR combination may refer to thecomputed check value or the received check value. The proper receptionmay be recognized by the one or more information units transmitted bythe communication device.

In a further embodiment, the communication device recognizes a receptionerror if the computed check value differs from the received check valueassociated with the given one of the one or more information units bymore than the XOR combination with the first predetermined value and ifthe computed check value differs from the received check valueassociated with the given one of the one or more information units by amore than the XOR combination with the second predetermined value. Forexample, the reception error may be recognized in the reception of theinformation unit by the communication device itself. The XOR combinationmay be with the computed check value or received check value. Thereception error may be recognized if the computed check value differs bymore than the XOR combination with the first predetermined value and bythe XOR combination with the second predetermined value.

According to another embodiment, a communication device is provided thatreceives one or more information units having associated one or morecheck values from a first communication device, and determines whetherthe one or more check values correspond with a respective informationunit according a first predetermined derivation rule or according to asecond predetermined derivation rule or do not correspond with therespective information unit, and initiates a retransmission of aninformation unit to the first communication device in dependence on thedetermination. For example, the communication device may be a networknode, a base station or a gNB. The first and second communicationdevices may be mobile communication devices, for example a first and asecond user equipment, UE. The first predetermined derivation rule maybe a rule for deriving a CRC at the side of the first communicationdevice in the case that a NACK condition is to be signaled, the secondpredetermined derivation rule may be a rule for deriving a CRC at theside of the first communication device in case that an ACK condition isto be signaled. The communication device may selectively initiate aretransmission. The determination may comprise a determination whetherthe one or more check values correspond with a respective informationunit according to a first predetermined derivation rule or according toa second predetermined derivation rule or do not correspond with therespective information unit.

This embodiment according to the invention is also based on the findingthat it is advantageous to provide a signaling of a ACK/NACK informationas to whether a received information unit has been properly received bya receiving communication device or not by using analteration/modification of a check value of another information unitthat is sent after the received information unit has been received,because such signaling may increase reliability and effectivity of thewhole communication while the needed bandwidth is not increased as theoverhead, in this case the check value, is not increased. Rather, thecheck value is double-used by piggybacking this information onto thecheck value using a reversible operation. This embodiment provides theadvantage that the feedback is not sent using a direct link between thesending communication device and the receiving communication device, butis relayed via a base station, what may help saving the bandwidth of thesidelink communication channel, and it is not necessary that thereceiving communication device has to wait until it has an informationunit to send to the sending communication device to be able to piggybackthe feedback information onto this information unit, rather aninformation unit for a different communication device can be used forpiggybacking and the base station can extract the respective feedbackinformation from it, thereby no additional bandwidth usage occurs.

In an embodiment, the communication device amends a check valueassociated with an information unit transmitted by the communicationdevice in dependence on the determination. For example, the check valuemay be a CRC value, but any other check value may be used. Theinformation unit may be control information in a PSCCH or data in aPSSCH. The information unit may be transmitted to the secondcommunication device, which may be for example a second user equipment(UE). The determination may comprise as to whether the one more checkvalues correspond with a respective information unit according to afirst predetermined derivation rule or according to a secondpredetermined derivation rule or do not correspond with the respectiveinformation unit, this may be used to selectively initiate theretransmission.

In a further embodiment, the communication device schedules anallocation of resources to multiple communication devices, wherein thecommunication device allocates a communication resource for theretransmission in dependence on the determination. For example, thedetermination comprises whether the one or more check values correspondwith respective information units according a first predeterminedderivation rule or according to a second predetermined derivation ruleor do not correspond with the respective information unit, this may beused to selectively initiate the retransmission.

In a further embodiment, the check value may allow for a detection ofbit errors within the information unit to which the check value isassociated. For example, the check value allows for a detection of biterrors at least up to a predetermined number of bit errors, and mayoptionally allow for the correction of bit errors, in order to improvethe communication.

In an embodiment, the check value is cyclic redundancy check value, CRC.

In an embodiment, the communication device computes the check valueassociated with an information unit transmitted by the communicationdevice on the basis of the information unit using a predeterminedcomputation rule to obtain a computed check value, the communicationdevice selectively applies a reversible modification to the computedcheck value in dependence on the determination to thereby obtain anamended check value for transmission or the communication device isconfigured to selectively apply a first reversible modification or asecond reversible modification to the computed check value in dependenceon the determination to thereby obtain an amended check value fortransmission. For example, the information unit may be controlinformation in a PSCCH or data in a PSSCH. The predetermined computationrule may be a generator polynomial. The reversible modification maycomprise an XOR operation with a predetermined value. The determinationmay comprise a determination whether the one or more received checkvalues correspond with a respective receive information unit accordingto a first predetermined derivation rule or according to a secondpredetermined derivation rule or whether they do not correspond with therespective information unit. The first and second reversiblemodifications may comprise XOR operations with first and secondpredetermined values respectively in the case a packet received from thesecond communication device has been properly received or has not beenproperly received, respectively. The determination may comprise adetermination whether the one or more received check values correspondwith a respective receive information unit according to a firstpredetermined derivation rule or according to a second predeterminedderivation rule or do not correspond with respective information unit.

In an embodiment, the communication device cooperates with a sendingcommunication device (for example, as discussed above) and with areceiving communication device (for example, as discussed above).

According to another embodiment, a system is provided that comprises acommunication device that serves as a base station, a communicationdevice that serves as a data sender communication device and acommunication device that serves as data receiver communication device,wherein the data sender communication device transmits one or moreinformation units directly to the data receiver communication device viaa sidelink and the data receiver communication device piggybacks anacknowledgement information signaling whether an information unit hasbeen properly received from the data sender communication device or notin a check value information.

This embodiment according to the invention is also based on the findingthat it is advantageous to signal an ACK/NACK condition using an amendedor modified checksum of a following transmission, thereby making thecommunication process more reliable without increasing complexity or theneed for additional bandwidth.

According to another further embodiment, there is provided a method forcommunication comprising receiving, at a communication device, one ormore information units from a second communication device, and amended acheck value associated with an information unit transmitted by thecommunication device in dependence on whether the information unitreceived from a second communication device has been properly receivedby the communication device or not, to thereby provide a signalingwhether the information unit received from the second communicationdevice has been properly received or not. For example, the informationunits may refer to data blocks or packets and/or control blocks orpackets or any other suitable units used to convey information. Theinformation units may be received from the second communication device,which may be a user equipment, via a direct link, but it is alsopossible to receive the information units via a base station. Theinformation unit transmitted by the communication device may be controlinformation in a PSCCH or data in a PSSCH, and may be transmitted by thecommunication device to a base station, e.g., a gNB, or to the secondcommunication device.

This method is based on the same considerations as the correspondingcommunication device.

According to another embodiment, a method is provided that comprisestransmitting, by a communication device, one or more information unitsto another communication device, receiving, at the communication device,one or more information units having associated one or more checkvalues, and deriving an information indicating whether the one or moreinformation units transmitted by the communication device have beenproperly received by the another communication device or not independence on the one or more check values. For example, the informationunits may be data blocks or data packets and/or control blocks orcontrol packets. The transmitting may be performed directly via asidelink without involving a base station, to which the communicationdevice could also communicate. The check values may be multibit binaryvalues, e.g., CRC values.

This method is based on the same considerations as the correspondingcommunication device.

According to another embodiment, a method for communication is providedthat comprises receiving, at a communication device, one or moreinformation units having associated one or more check values from afirst communication device and determining whether the one or more checkvalues correspond with the respective information unit according to afirst predetermined derivation rule or according to a secondpredetermined derivation rule or do not correspond with the respectiveinformation unit, and initiating a retransmission of an information unitto the first communication device in dependence on the determination.For example, the communication devices may be mobile communicationdevices, e.g., user equipment. The step of determining may be performedat the communication device, and the first predetermined derivation rulemay be a rule for deriving a CRC at the site of the first communicationdevice in case a NACK condition is to be signaled, the secondpredetermined derivation rule may be a rule for deriving a CRC at thesite of the first communication device in the case that an ACK conditionis to be signaled. The determination may comprise determining whetherthe one or more check values correspond with a respective informationunit according to a first predetermined derivation rule or according tothe second predetermined derivation rule or do not correspond with therespective information unit.

This method is based on the same considerations as the correspondingcommunication device.

The above-mentioned methods are optionally be supplemented by one of thefeatures and functionalities described herein with respect to thecorresponding communication devices.

In a further embodiment, a computer program is provided for performingone of the aforementioned methods.

In accordance with a further embodiment, a communication device, e.g. aso-called receiving communication device, is provided which is receivingone or more information units from a second communication device, andwhich transmits a feedback information in a wireless resource unit whichis reserved for a transmission of a different communication device butwhich is not used or only partly used by the different communicationdevice. For example, the information units may be data blocks or packetsand/or control blocks or packets. The communication devices may bemobile communication devices, e.g., user equipment. The communicationdevice may receive the information units from the second communicationdevice via a direct link, e.g., using a sidelink. The feedbackinformation may comprise an acknowledgement information and/or a channelquality indicator, CQI, information and/or a rank indicator, RI,information indicating, e.g., in a MIMO device or system, how manyspatial layers to transmit, the RI may be used for devices for multipleantennas for sidelink transmission. Further, the feedback informationmay be a precoding matrix indicator, PMI, information and/or channelstate information, CSI. The wireless resource unit may refer to aresource block pool which is reserved, i.e., allocated or scheduled forexample by a base station making the resource allocation, for thetransmission to a different communication device, this differentcommunication device may be one of a plurality of communication deviceslike a second, third, fourth or fifth user equipment. The reservedwireless resource unit may be unused or only partly used, i.e., notcompletely used, in general, which means at least partly unused.

This embodiment according to the invention is based on the finding thatit is advantageous to signal a feedback information by using an, atleast partly, unused part of a resource unit that is not reserved forthe receiving communication device but for a different communicationdevice, because this allows for the provision of feedback withoutrequiring that an own resource is dedicated for such feedback, therebyhelping to save bandwidth and resources while helping to increasereliability. Moreover, it has been found that using such a resource thatis reserved for a different communication device but not used by thedifferent communication device for the signaling of feedback informationdoes not affect the usability or availability of the resource for thecommunication device for which the resource is reserved because thefeedback is inserted only into unused resources, e.g. into parts of thebandwidth that are ‘empty’, i.e. not carrying a payload, anyway. By thistechnique, a double-use of a resource unit that is reserved for adifferent communication device is provided without having to increasecomplexity of the resource unit or without having to reserve or allocatea resource for the communication device that wished to transmit feedbackinformation. In particular, the fact that resources are allocated todevices in a “precautionary” manner, without having certainty that thedevices will actually use the resources, can be exploited. In case thedifferent communication device has a resource demand, it will typicallynot be affected, but in case it does not actually use a precautionaryallocated wireless resource, this wireless resource will nevertheless beused for the feedback (by another device, other than the device forwhich the wireless resource is reserved).

In an embodiment, the communication device transmits, as the feedbackinformation, an acknowledgment information indicating whether the one ormore information units received from the second communication devicehave been properly received or not.

In another embodiment, the communication device transmits, as thefeedback information, a channel quality indicator, CQI, informationdescribing a channel quality, which may be in the form of a scalarchannel value, the communication device transmitting, as the feedbackinformation, a rank indicator, RI, information describing a transmissionrank to use or a number of spatial layers to use by the transmitter totransmit data, and/or the communication device transmits, as thefeedback information, a precoding matrix indicator, PMI, informationdescribing which precoding matrix would be used for transmission towardsthe communication device, and/or the communication device transmits, asfeedback information, a channel state information, CSI, describing astate of a channel, for example for multiple antennas, this informationmay be transmitted in the form of a set of a plurality of channelcoefficients.

In another embodiment, the communication device identifies a wirelessresource unit which is reserved for a transmission of a differentcommunication device and which is at least partly unused for thetransmission of the feedback information. Reserved, may, for example,refer to allocated or scheduled, for example by a base station makingthe resource allocation. The identifying may be performed, for example,by detecting whether the resource unit is used or by sensing occupancyof the resourced unit.

In an embodiment, the communication device monitors a transmissionactivity in a wireless resource unit which is reserved for atransmission of the different communication device, and wherein thecommunication device is configured to identify the monitored wirelessresource unit for the transmission of the feedback information if it isfound that the wireless transmission unit is at least partially unused.The monitoring may be performed by listening to a transmission activity,e.g., utilizing listen-before-talk (LBT) or CSMA/CA techniques. Thewireless resource unit may be a physical wireless resource unit reserve,e.g., allocated or scheduled for example, by a base station making theresource allocation.

In a further embodiment, the communication device determines whether aportion of the wireless resource unit, the wireless resource unit beingreserved for a transmission of a different communication device, isunused and using a subsequent portion of said wireless resource unit forthe transmission of the feedback information. The portion of thewireless resource unit may refer to a first part of a subframe orshortened transmission time interval (sTTI) consisting of a few symbols,and reserve may refer to allocated or schedule, for example, by a basestation making the resource allocation. The subsequent portion may referto a portion immediately following the portion which has been identifiedas unused, for example, a second part of the subframe.

In another embodiment, the communication device monitors a plurality ofwireless resource units which are reserved for a transmission of one ormore different communication devices in order to identify a wirelessresource unit which is at least partially unused for the transmission ofthe feedback information. The wireless resource unit which is at leastpartially unused may even be completely unused.

In a further embodiment, a communication device receives a resourceallocation information from a managing communication device, this may bea base station, e.g., a gNB, wherein the resource allocation informationdescribes an allocation of wireless communication resources, forexample, of wireless resource units to different communication devices,which may be, in examples, a reservation of wireless communicationresources, and indicates which wireless communication resources areuseable for transmission of feedback information by communicationdevices other than the communication devices to which the respectivewireless communication resources are allocated. For example, it may beindicated which wireless communication resources are usable in the casethat the communication device to which the wireless communicationresource is allocated to does not make use, or does not make full use,of the wireless communication resource.

In another embodiment, the communication device is configured to use thereceived resource allocation information for deciding which wirelessresource unit to use for the transmission of the feedback information.For example, the communication device may be configured to transmitgiven the resource allocation information from the feedback transmittingcommunication device, which may be a user equipment. In examples, thespace to transmit feedback may be limited, in order to save bandwidth,for example, to wireless resource units indicated in a resourceallocation information.

In an embodiment, the communication device selectively monitors atransmission activity in wireless resource units, which may be physicalwireless resource units, which are reserved for a transmission of adifferent communication device in the received resource allocationinformation and which are marked to be usable for transmission offeedback information in the received resource allocation information, toidentify an at least partially unused wireless resource unit for thetransmission of the feedback information. For example, the reservedwireless resource units may be allocated or schedule, for example by abase station making resource allocation.

According to another embodiment, a communication device, e.g. aso-called sending communication device, is provided that transmits oneor more information units to another communication device, e.g. aso-called receiving communication device, and monitors a resource unit,which is not allocated to the another communication device, but reservedfor a transmission of a communication device which is different from theanother communication device for a feedback information from the anothercommunication device. For example, the information units may be datablocks or packets and/or control blocks or packets, and thecommunication devices may be mobile communication devices such as userequipment. The communication device may transmit to another (i.e. theanother) communication device directly via a sidelink without involvinga base station to which the communication device could also communicate.In examples, the resource unit may be a wireless resource unit, and/orthe resource unit may be reserved for a transmission of thecommunication device or any of further communication devices, which alsomay be user equipment.

This embodiment according to the invention is also based on the findingthat it is advantageous to provide feedback information to a receivingcommunication device that has received an information unit(s) sent bythe sending communication device by using an, at least in part, unusedpart of a resource unit which is not reserved for the receivingcommunication device but for a different communication device, becausethis allows for the provision of feedback without requiring that aresource is dedicated for such feedback what may help saving bandwidthand resources while increasing reliability. Moreover, it has been foundthat using such a resource that is reserved for a differentcommunication device but not used by the different communication devicefor the signaling of feedback information does not affect the usabilityor availability of the resource for its original purpose. Moreover, ithas been found that such a double-usage of the resource may maintain thesize of the reserved bandwidth or may even increase the ratio betweenthe amount of data transmitted and the reserved bandwidth.

Moreover, the same considerations mentioned above for the correspondingreceiving communication device also apply.

In a further embodiment, the communication device monitors a resourceunit, which is not allocated to another (i.e. the another) communicationdevice, but is reserved for a transmission of a communication devicewhich is different from the another communication device for anacknowledgment information signaling whether the one or more informationunits transmitted by the another communication device have been properlyreceived by the another communication device. For example, the resourceunit may be reserved for transmission of the communication device or ofany other communication devices. In examples, said acknowledgementinformation constitutes the signaling information or is a part of thefeedback information.

In a further embodiment, the communication device receives, as thefeedback information, a channel quality indicator, CQI, informationdescribing a channel quality, which may, in an example, be in the formof a scalar channel value, and/or wherein the communication devicereceives, as the feedback information, a rank indicator, RI, informationdescribing the transmission rank to use or the number of spatial layersto use by the transmitter, e.g., of the communication device, totransmit data, and/or wherein the communication device receives as thefeedback information a precoding matrix indicator, PMI, informationdescribing which precoding matrix should be used for transmissiontowards the communication device, e.g. for multiple antenna MIMOsidelink communication, and/or wherein the communication device receivesas the feedback information a channel state information, CSI, describinga state of a channel. For example, this may be in the form of a set of aplurality channel coefficients, e.g. for multiple antenna MIMO sidelinkcommunications.

In another embodiment, the communication device monitors a plurality ofwireless resource units which are reserved for a transmission of adifferent communication device which is different from another (i.e. theanother) communication device, e.g., different from another userequipment, in order to identify a wireless resource unit which is usedby another communication device, which may also be a user equipment, forthe transmission of the feedback information. A wireless resource unitmay e.g. include the NR numerology, time-f req-space with flexiblesubcarrier spacing (SCS), wideband and narrowband (NB), if a number ofaggregated carriers. For narrowband IoT devices, aggregates NBs shouldbe supported. For example, wireless resource unit may include, e.g., NRnumerology, time-frequency-space, optionally with flexible subcarrierspacing (SCS), wideband as well as narrowband (NB). In the case thate.g. narrowband IoT devices are involved, aggregated NBs should besupported.

In yet another embodiment, the communication device detects acharacteristic pattern which is allocated to another (i.e. the another)communication device, to recognize a transmission of a feedbackinformation by another communication device, for example, thecharacteristic pattern may be a characteristic scrambling sequence.

In another embodiment, the communication device receives a resourceallocation information for a managing communication device, which may bea base station, e.g., a gNB, wherein the resource allocation informationdescribes an allocation of wireless communication resources to differentcommunication devices and indicates which wireless communicationresources are useable for a transmission of feedback information bycommunication devices other than the communication devices to which therespective wireless communication resources are allocated. For example,the wireless communication resources may be wireless resource units, andthe allocation of the wireless communication resources may be referredto a reservation of wireless communication resources. The indicationwhich wireless communication resources are usable may be for the casethat the communication device, to which the wireless communicationresources are allocated, does not make use, or does make full use, ofthe wireless communication resource.

In another embodiment, the communication device uses the receivedresource allocation information for limiting a number of wirelessresource units monitored for feedback from another (i.e. the another)communication device. For example, only such wireless resource units maybe monitored which are indicated as usable for transmission of feedbackinformation by communication devices other than the communication deviceto which the respective wireless communication resources are allocated.

In another embodiment, the communication device selectively monitors atransmission activity in wireless resource units, which may be physicalwireless resource units which are reserved, e.g., allocated or scheduledfor example by a base station making the resource allocation, fortransmission of a different communication device, which may be differentfrom the another communication device, in the received resourceallocation information in which are marked to be usable for transmissionof a feedback information in the received resource allocationinformation, to find the feedback information.

In a further embodiment, the communication device searches, e.g.,selectively, for the feedback information in one or more wirelessresource units which are at least partially unused, for example in aportion of a wireless resource unit following an unused initial portionof said wireless resource unit.

In another embodiment, the communication device only searches wirelessresource units, an initial portion of which is unused, for the feedbackinformation.

According to another embodiment, a communication device coordinates aresource allocation to a plurality of communication devices andcommunicates with the plurality of communication devices, wherein thecommunication device provides a resource allocation information to theplurality of communication devices, wherein the resource allocationinformation describes an allocation of wireless communication resourcesto different communication devices and indicates which wirelesscommunication resources are usable for transmission of feedbackinformation by communication devices other than the communicationdevices to which the respective wireless communication resources areallocated. For example, the communication device may be a base station,e.g., a gNB. The allocation of wireless communication resources mayrefer to a reservation of wireless communication resources, and wirelesscommunication resources may refer to wireless resource units. Indicatingwhich wireless communication resources are usable may be performed inthe case that the communication device to which the wirelesscommunication resource is allocated does not make use, or does make fulluse, of the wireless communication resource, for example.

This embodiment according to the invention is also based on the findingthat it is advantageous to transmit a feedback information from areceiving communication device by using a part of a resource unit, thepart being unused by the communication device for which it is (primarilyor preferentially) reserved, the resource unit not being reserved forthe receiving communication device but for a different communicationdevice. It has been found that informing the communication devices abouta current resource allocation by providing a resource allocationinformation helps to double-use a resource allocated to a differentcommunication device, the resource being allocated but not fully used bythe communication device for which it is reserved without an increasecomplexity of the resource unit or without need to reserve or allocate aresource for the communication device that wished to transmit feedbackinformation. For example, it may be signaled that a wireless resource ispreferentially (or prior-ranking) reserved for a given communicationdevice, but that this wireless resource may be (in a lower-rankingmanner) used by one or more other communication devices for a feedback.Thus, resource efficiency is improved. On the other hand, communicationdevices who want to transmit a signaling or communication devicesexpecting a feedback do no longer need to monitor all available wirelessresources for free wireless resources or for wireless resourcescomprising a feedback information. Rather, the signaling of wirelessresources with may be used (in a lower ranking manner) for atransmission of feedback reduces the “search space” for identifyingwireless resources useable or used for feedback transmission.

In an embodiment, the communication device identifies wireless resourceunits which are only partially used by the communication devices towhich the respective wireless resource units are allocated, and marksthe wireless communication units which are only partially used by thecommunication devices to which they are allocated as being usable fortransmission of feedback information by communication devices other thanthe communication devices to which the respective wireless communicationresources are allocated in the allocation information. For example, thecommunication device may be a base station, e.g., a gNB, and thewireless communication resources may refer to wireless resource units.

In another embodiment, the communication device monitors a usage ofwireless resource units by the plurality of communication devices andmarks wireless resource units, a usage of which is below or equal to apredetermined threshold value as being usable for transmission offeedback information by communication devices other than thecommunication devices to which the respective wireless resource unitsare allocated in the allocation information, or the communication devicemarks one or more wireless resource units having a relatively smallusage as being usable for transmission of feedback information bycommunication devices other than the communication devices to which therespective wireless resource units are allocated in the allocationinformation.

According to another embodiment, a system is provided comprising acommunication device which serves as a base station, a communicationdevice serving a data sender communication device and a communicationdevice serving as a data receiver communication device, wherein the datasender communication device transmits one or more data units directly tothe data receiver communication devices via a sidelink, and wherein thedata receiver communication device is configured to transmit anacknowledgement information signaling whether an information unit hasbeen properly received from the data sender communication device or not.

This embodiment according to the invention is also based on the findingthat it is advantageous to signal a feedback information by using an, atleast partly, unused part of a resource unit that is not reserved forthe receiving communication device but for a different communicationdevice, because this allows for the provision of feedback withoutrequiring that an own resource is dedicated for such feedback therebyhelping to save bandwidth and resources while helping to increasereliability.

According to another embodiment, a method for communication is providedthat comprises receiving, at a communication device, one or moreinformation units from a second communication device, further comprisingtransmitting a feedback information in a wireless resource unit which isreserved for transmission of a different communication device but whichis not used or only partially used by the different communicationdevice. For example, the method may be performed by a firstcommunication device which may be a user equipment. The one or moreinformation units may be data blocks or packets and/or control blocks orpackets and may be received from a second communication device, e.g.,user equipment 2, via a direct link. The feedback information may forexample refer to acknowledgment information and/or channel qualityindicator, CQI, information and/or rank indicator, RI, information or aprecoding matrix indicator, PMI, information and/or channel stateinformation, CSI. A wireless resource unit may be a unit of a resourceblock pool which is reserved, e.g., allocated or scheduled for example,by a base station making resource allocation. The differentcommunication device may be different from the wireless communicationdevice, e.g., the first wireless communication device. Not used or onlypartially used may refer to not completely used, generally speaking,which is at least partly unused.

This method is based on the same considerations as the correspondingcommunication device.

According to another embodiment, the method for communication comprisestransmitting, by a communication device, one or more information unitsto another communication device, and comprises monitoring a resourceunit, which may be a wireless resource unit, which is not allocated tothe another communication device, but reserved for a transmission of acommunication device which is different from the another communicationdevice for a feedback information from the another communication device.For example, the communication devices may be mobile communicationdevices such as user equipment. The information units may refer to datablocks or packets and/or control blocks or packets, the transmitting maybe performed directly via a sidelink without involving a base station,to which the communication device could also communicate. The monitoringmay be performed, e.g., by the communication device and the resourceunit may be reserved for transmission of the communication device or anyother of further communication devices.

This method is based on the same considerations as the correspondingcommunication device.

According to another embodiment, a method for communication comprisescoordinating a resource allocation to a plurality of communicationdevices, the method comprises providing a resource allocationinformation to the plurality of communication devices, wherein theresource allocation information describes an allocation of wirelesscommunication resources to different communication devices and indicateswhich wireless communication resources are usable for transmission offeedback information by communication devices other than thecommunication devices to which the respective wireless communicationresources are allocated. For example, the coordinating may be performedby a communication device base station, e.g., a gNB. The allocation mayrefer to a reservation of wireless communication resource, wirelesscommunication resources may refer to wireless resource units. Theindication may be performed in the case that the communication device towhich the wireless communication resource is allocated does not makeuse, or does not make full use, of the wireless communication resource.

This method is based on the same considerations as the correspondingcommunication device.

The above-mentioned methods are optionally be supplemented by one of thefeatures and functionalities described herein with respect to thecorresponding communication devices.

According to another embodiment, a computer program is provided forperforming the method of the previous embodiments.

In accordance with another embodiment, a communication device isprovided that receives one or more information units, which may be datablocks or packets and/or control blocks or packets, from a plurality ofother communication devices, wherein the communication device receives aresource allocation message from a managing communication device,wherein the resource allocation message defines an allocation of bitpositions associated with an acknowledgement of information unitsreceived from the plurality of other communication devices in a combinedacknowledgement information unit, and wherein the communication devicetransmits a combined acknowledgement information unit in response to areception of information units from a plurality of other communicationdevices using the allocation of bit positions defined in the resourceallocation message. For example, the communication device may be amobile communication device, e.g., a user equipment UE. The techniqueused may refer to the concept of multicast HARQ. The communicationdevice may receive the information units via a direct link withoutinvolvement of a base station, e.g., multiple unicast transmissions froma number of transmitting communication devices, which may be userequipment. The combined acknowledgement information unit may refer to aD2D/V2X bundled broadcast, a multicast, a groupcast or a unicast HARQ.The bit positions may refer to an UE acknowledgement bit, which may bedefined in the resource allocation message, for example, such that onebit in a multibit packet or transmission unit is associated with areception status, ACK/NACK of a respective information unit receivedfrom a respective one of the other communication devices.

This embodiment according to the invention is based on the finding thatit is advantageous to provide a signaling of an acknowledgementinformation in a combined acknowledgement information unit because thisallows that in a system where a communication device communicates with aplurality of communication devices, a single combined acknowledgementinformation unit can be used for signaling respective acknowledgementinformation, the structure (i.e. bit positions of acknowledgementinformation for each of the plurality of communication devices) of thecombined acknowledgement information unit being defined in a resourceallocation message being communicated to the plurality of communicationdevices. Using a single combined acknowledgement information unit mayhelp to save resources that would be used by an individual provision offeedback information by each of the plurality of communication devicesat the cost of transmitting the resource allocation message. Moreover,it has been found that using such a combined acknowledgement informationunit may give a quick and efficient overview for a managingcommunication device as to which communication device may be needed totrigger a retransmission or to adapt a communication mode to a morerobust or reliable communication. Also, having a flexibly configurableallocation of bit positions to communication devices allows for anadaptation to the communication environment, for example on the basis ofknowledge which of the communication devices will receive informationunits from many other communication devices and from which subset of afull set of communication devices the information units will bereceived.

In another embodiment, the communication device broadcasts or multicastsor groupcasts the combine acknowledgement information unit. For example,this may be a feedback of multicast/groupcast UE with a multibit HARQ.For example, broadcasting may imply that every device in the area ofcoverage gets this HARQ.

In another embodiment, the communication device broadcasts the combinedacknowledgment information unit to the other communication devices via asidelink which does involve a base station (BS), are a managingcommunication device. For example, the multicast/groupcast HARQ may betransmitted via sidelink.

In an embodiment, the communication device sets bits at bit positionsassociated with one or more other communication devices from which oneor more information units were properly received to a first bit valueand set bits at bit positions associated with one or more othercommunication devices from which one or more information units were notproperly received or from which no information units were received to asecond value which is different from the first value. For example, thebit positions may be bit positions of the combined acknowledgmentinformation unit, and the first bit value may be one and the second bitvalue may be zero. In an embodiment, this may be a configuration to setup a multicast/groupcast message for all other UEs.

In another embodiment, the communication device transmits a combinedacknowledgment unit for information units received from different othercommunication devices within a predetermined period of time, e.g.,within a certain time interval. For example, the transmission shouldoccur within a certain predetermined time interval.

In another embodiment, the resource allocation message also defines inwhich wireless resource unit, e.g., timeslot, time-frequency region,time-frequency-code region, numerology etc., the combinedacknowledgement information unit is to be transmitted, and wherein thecommunication device transmits the combined acknowledgement informationunit in the wireless resource unit specified by the resource allocationmessage. For example, the multicast/groupcast message could betransmitted with a certain allocated resource. Optionally, as an updateor extension, a multicast/groupcast HARQ to be transmitted in anautonomous mode as well as for an out of coverage mode, is defined.

In another embodiment, the communication device evaluates a resourceallocation message which is piggy-backed on data. For example, thisresource allocation message may be advantageously received from a basestation, which may optionally comprise a feedback toggle informationwhich may switch between a provision of individual feedback and aprovision of a combined acknowledgement information unit.

According to another embodiment, there is provided a communicationdevice that transmits one or more information units to anothercommunication device and receives a resource allocation message from amanaging communication device, wherein the resource allocation messagedefines an allocation of bit positions associated with anacknowledgement of information units received by the anothercommunication device in a combined acknowledgement information unit andwherein the communication device receives a combined acknowledgementinformation unit and evaluates at a bit position defined by the resourceallocation message in order to derive an information whether one or moreinformation units transmitted by the communication device have beenproperly received by the another communication device or not. Forexample, the communication device may be one of a number of mobilecommunication devices, for example many feedback-receiving userequipment. The information units may be data blocks or packets and/orcontrol blocks or packets and may be transmitted directly via asidelink, without involving a base station, to which the communicationdevice could also communicate. The bit at a bit position defined by theresource allocation message may be defined as being associated with anacknowledgement of an information unit received by another (i.e. theanother) communication device, e.g., user equipment 1, from thecommunication device itself.

This embodiment according to the invention is also based on the findingthat it is advantageous to signal an acknowledgement information in acombined acknowledgement information unit, this allows that in a systemin which a communication device communicates with a plurality ofcommunication devices, a single combined acknowledgement informationunit can be used for signaling respective acknowledgement information.The structure (i.e. bit positions of acknowledgement information foreach of the plurality of communication devices) of the combinedacknowledgement information unit being defined in a resource allocationmessage may be communicated to the plurality of communication devices.

In an embodiment, the communication device retransmits an informationunit to another (i.e. the another) communication device in case theevaluated bit of the combined acknowledgement information unitsindicates the previous transmission of said information unit was notproperly received by another communication device. The communicationdevice may, for example, selectively retransmit the information unit, itis also possible to retransmit the HARQ broadcast as unicast. Forexample, the evaluated bit may be at the bit position defined by theresource allocation message.

In an embodiment, the resource allocation message also defines in whichwireless resource unit, e.g., timeslot, time-frequency region,time-frequency-code region, etc., the combined acknowledgementinformation unit is to be transmitted and wherein the communicationdevice receives the combined acknowledgement information unit in thewireless resource unit specified by the resource allocation message. Forexample, a receiving communication device, e.g., a receiving UE, couldmonitor resources needed to receive the HARQ information.

In an embodiment, the communication device evaluates a resourceallocation message which is piggybacked on data. The resource allocationmessage may be advantageously received from a base station, and mayoptionally comprise a feedback toggle information which may switchbetween a reception of individual feedback and a reception of a combineacknowledgment information unit.

According to a further embodiment, a communication device, e.g. amanaging communication device, coordinates a resource allocation to aplurality of communication devices and communicates with the pluralityof communication devices wherein the communication device provides aresource allocation information to the plurality of communicationdevices, wherein the resource allocation information defines anallocation of bit positions associated with an acknowledgement ofinformation units received by a given communication device from aplurality of other communication devices in the combined acknowledgementinformation unit to be transmitted by the given communication device inresponse to a reception of information units from a plurality of theother communication devices. For example, the communication device maybe a base station, for example a gNB or an eNB scheduling the resourcesand bit positions. The given communication device and the plurality ofother communication devices may be mobile communication devices, e.g.,user equipments.

This embodiment according to the invention is also based on the findingthat it is advantageous to signal an acknowledgement information in acombined acknowledgement information unit, this allows that in a systemin which a communication device communicates with a plurality ofcommunication devices, a single combined acknowledgement informationunit can be used for signaling respective acknowledgement information.The structure (i.e. bit positions of acknowledgement information foreach of the plurality of communication devices) of the combinedacknowledgement information unit being defined in a resource allocationmessage is communicated by the managing to the plurality ofcommunication devices. Moreover, it has been found that using such acombined acknowledgement information unit may give a quick and efficientoverview for the managing communication device as to which communicationdevice of the plurality of communication devices may be needed totrigger a retransmission or to adapt a communication mode to a morerobust or reliable communication.

In another embodiment, the communication device provides resourceallocation information allocating wireless resource units fortransmissions from multiple other communication devices to the givencommunication device via a sidelink which does not involve thecommunication device itself. For example, the communication device maybe a base station, e.g. a gNB. The other communication devices may beuser equipments. For example, the communication device allocatesresources and does not participate in the communication of the data oversidelink.

In another embodiment, the communication device identifies acommunication device to which a plurality of other communication devicescan send information units on the basis of allocation of wirelessresource units, the communication device may be a gNB, and the othercommunication devices may be mobile communication devices, e.g., userequipments, wherein the communication device reserves a wirelessresource unit for the combined acknowledgement information unit to betransmitted by the identified communication device in response to theidentification of the communication device, and allocates the bitpositions within the acknowledgement information unit in dependence on aknowledge which other communication devices have wireless resource unitsallocated for transmission to the identified communication device. Forexample, the base station, e.g. gNB, may use its knowledge about theallocation of wireless resource units, and the base station, identifiesfeedback multicasting user equipments and feedback receiving userequipments, also it may reserve the allocated resource for this bundledHARQ.

In an embodiment, the communication device includes the resourceallocation information into an individual device downlink controlinformation, e.g., a 5G DCI, or into a group downlink controlinformation, e.g., 5G group DCI. In examples, the communication deviceor base station may utilize downlink control information to convey thisresource allocation information.

In another embodiment, the communication device multicasts/groupcaststhe resource allocation information to a plurality of communicationdevices, which may be user equipments, wherein the resource allocationinformation comprises an allocation of a wireless resource unit for thecombined acknowledge information unit, e.g., sidelink transmissionresources for which to transmit the broadcast HARQ feedback message fora user equipment and/or sidelink reception pool resources for which toreceive the broadcast HARQ feedback message from the user equipment,e.g., an information in which wireless resource unit the combinedacknowledgement information unit is to be transmitted, and allocation ofpositions, e.g., HARQ bit position information, associated with anacknowledgement of information units received by a given communicationdevice, e.g., a user equipment, from a plurality of other communicationdevices, e.g., further user equipment, in a combined acknowledgementinformation unit, and a message size information, e.g., the message sizeof an aggregated HARQ feedback, describing a message size of thecombined acknowledgment information unit. This may define, for example,the properties of this resource allocation information message.

In an embodiment, the communication device, e.g., a gNB, dynamicallyupdates the resource allocation information, for example the resourceinformation may be dynamically allocated.

In another embodiment, the communication device, e.g., the gNB, monitorsa communication between other communication devices, e.g., between userequipments, and identifies a communication device, e.g., a first userequipment, to which a plurality of other communication devices, e.g.,the other user equipments, send information units within a predeterminedperiod of time on the basis of the monitoring, and reserves a wirelessresource unit for the combined acknowledgement information unit to betransmitted by the identified communication device in response to theidentification of the communication device, and allocates the bitpositions within the combined acknowledgement information unit independence on a knowledge which other communication devices havetransmitted information units to the identified communication devicewithin the predetermined period of time. In an example, the base stationmay monitor the resources for dynamic allocation and reservation,including bit positional information.

In another embodiment, the communication device provides at least a partof the resource allocation information piggybacked on data. This mayoptionally comprise a feedback toggle information which may switch othercommunication devices between a provision of individual feedback and aprovision of a combined acknowledgement information unit.

According to a further embodiment, there is provided a method forcommunication comprising receiving, at a communication device, one ormore information units from a plurality of other communication devices,the method comprising receiving, e.g. at the communication device, aresource allocation message from a managing communication device,wherein the resource allocation message defines an allocation of bitpositions associated with an acknowledgement of information unitsreceived from the plurality of other communication devices in a combinedacknowledgement information unit, and the method comprising transmittinga combined acknowledgement information unit, e.g., a D2D bundledbroadcast HARQ, in response to a reception of information units from aplurality of other communication devices using the allocation of bitpositions defined in the resource allocation message. The informationunits may, for example, be data blocks or packets and/or control blocksor packets and may be received via direct links, without involvement ofbase station, e.g., multiple unicast transmission from a number oftransmitting communication devices, the communication devices may forexample be user equipments. The allocation of bit position may berespective user equipment acknowledgment bits, and the resourceallocation message may specify for example that one bit in a multibitpacket or transmission unit is associated with a reception status,ACK/NACK, of a respective information unit received from a respectiveone of the other communication devices.

This method is based on the same considerations as the correspondingcommunication device.

According to an embodiment, there is provided a method forcommunication, the method comprising transmitting, by a communicationdevice, which may be a user equipment, one or more information units,which may be data blocks or packets and/or control blocks or packets toanother communication device, which may be a user equipment, and themethod comprising receiving, e.g., at the communication device, aresource allocation message from a managing device, wherein the resourceallocation message defines an allocation of bit positions associatedwith an acknowledgement of information units received, by the anothercommunication device, from a plurality of communication devices in acombined acknowledgement information unit, and the method comprisingreceiving, e.g., at the communication device, a combined acknowledgementinformation unit, and evaluating a bit at a bit position defined by theresource allocation message in order derive information whether one ormore information units transmitted by the communication device has beenproperly received by the another communication device or not. Forexample, the one or more information units may be transmitted directlyvia a sidelink without involving a base station, to which thecommunication device could also communicate. In an example, the bitposition may be defined as being associated with an acknowledgment of aninformation unit from the communication device.

This method is based on the same considerations as the correspondingcommunication device.

According to an embodiment, a method for communication is provided,comprising coordinating, by a communication device, a resourceallocation to a plurality of communication devices, comprising providinga resource allocation information to the plurality of communicationdevices, wherein the resource allocation information defines anallocation of bit positions associated with an acknowledgement ofinformation units received by a given communication device, e.g., afirst user equipment, from a plurality of other communication devices,e.g. further user equipments, in a combined acknowledgement informationunit to be transmitted by the given communication device in response toa reception of information units from a plurality of the othercommunication devices.

This method is based on the same considerations as the correspondingcommunication device.

The above-mentioned methods are optionally be supplemented by one of thefeatures and functionalities described herein with respect to thecorresponding communication devices.

According to an embodiment, a computer program is provided forperforming a method according to the previously mentioned embodiments,when the computer program is run on a computer.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention will be detailed subsequentlyreferring to the appended drawings, in which:

FIG. 1 shows a block diagram of a communication device according to anembodiment of the present invention;

FIG. 2 shows a block diagram of a of a communication device according toan embodiment of the present invention;

FIG. 3 shows a block diagram of a further communication device accordingto an embodiment of the present invention;

FIG. 4 shows a conceptual layout of a system according to an embodimentof the present invention;

FIG. 5 shows a flow chart of a method for a communication deviceaccording to an embodiment of the present invention;

FIG. 6 shows a flow chart of a method for a communication deviceaccording to an embodiment of the present invention;

FIG. 7 shows a flow chart of a method for communication for acommunication device according to an embodiment of the presentinvention;

FIG. 8 shows a layout of an illustrative system to convey HARQ feedbackinformation according to an embodiment of the present invention;

FIG. 9 shows a layout of another illustrative system to convey HARQfeedback information according to an embodiment of the presentinvention;

FIG. 10 shows a conceptual illustration on how the HARQ feedback isconveyed according to an embodiment of the present invention;

FIG. 11 shows a conceptual block diagram of a method performed bytransmitter and receiver according to an embodiment of the presentinvention;

FIG. 12 shows the conceptual block diagram of FIG. 11 in the case thatan ACK indication is to be sent according to an embodiment of thepresent invention;

FIG. 13 shows a block diagram of a communication device according to anembodiment of the present invention;

FIG. 14 shows a block diagram of another communication device accordingto another embodiment of the present invention;

FIG. 15 shows a block diagram of a communication device according to afurther embodiment of the present invention;

FIG. 16 shows a conceptual arrangement of a system according to afurther embodiment of the present invention;

FIG. 17 shows a flow chart of a method for a communication device, e.g.an user equipment, according to an embodiment of the present invention;

FIG. 18 shows a flow chart of a method for a communication device, e.g.an user equipment, according to a further embodiment of the presentinvention;

FIG. 19 shows a flow chart of a method for a communication device, e.g.a base station, according to another embodiment of the presentinvention;

FIG. 20 shows a schematic diagram of a slot of a subframe allocated forsidelink communications according to an embodiment of the presentinvention;

FIG. 21 shows a conceptual overview over the structure of a transmissionresource pool for an embodiment of the present invention;

FIG. 22 shows a conceptual drawing of a communication device, e.g. auser equipment, according to an embodiment of the present invention;

FIG. 23 shows a conceptual drawing of a communication device, e.g. auser equipment, according to an embodiment of the present invention;

FIG. 24 shows a conceptual drawing of a communication device, e.g. abase station, according to an embodiment of the present invention;

FIG. 25 shows a flow chart of a method for a communication device, e.g.a user equipment, according to an embodiment of the present invention;

FIG. 26 shows a flow chart of a method for a communication device, e.g.a user equipment, according to an embodiment of the present invention;

FIG. 27 shows a flow chart of a method for a communication device, e.g.a managing communication device, according to an embodiment of thepresent invention;

FIG. 28 shows an overview of a system comprising a plurality ofcommunication devices according to an embodiment of the presentinvention;

FIG. 29 shows a diagram of option 1 of a group multicast HARQ resourceallocation according to an embodiment of the present invention;

FIG. 30 shows a diagram of option 2 of a HARQ resource allocation viadownlink control according to an embodiment of the present invention;and

FIG. 31 shows a general structure of a subframe and resource block pool.

DETAILED DESCRIPTION OF THE INVENTION

In the following, different embodiments according to the invention willbe described. However, it should be noted that functionalities describedwith respect to different of the embodiments can also be combined. Also,the embodiments described here should not be considered as limiting thescope.

First, some general consideration, which should be considered asadvantageous but not as being necessary, with respect to a communicationenvironment, in which embodiments according to the invention can beused, will be described.

In communication systems, it is possible that communication devices sendtheir transmissions via a base station to each other, or they cancommunication directly. In either case, it is advantageous to provide asignaling as to whether or not data packets have been properly received.Such signaling may enhance the reliability of the communication process.

An illustrative communication system comprises a single base stationsupporting sidelink (SL) transmissions and two communication devices,UE1 and UE2, where UE 2 is transmitting to UE 1 (in a typical D2D or V2Xscenario). UE1 has received some data from UE2 via a unicast SLtransmission. UE2 is expecting a hybrid automatic repeat request, HARQ,feedback, from UE1 regarding the outcome of its first transmission, eachtransmission may be defined a HARQ process ID.

Scrambling Feedback with UE Blind Decoding

In the following, some embodiments according to the invention will bedescribed which use an amended check sum for a signaling.

In order to provide for a HARQ signaling, communication resources may bereserved for this kind of signaling. If such a resource is not provided,it is more difficult to find a way to provide this signaling. Accordingto the present application, there are two scenarios for embedding HARQfeedback and transmitting it back to the appropriate user equipment.

A) The HARQ feedback may be embedded and transmitted along the SL ineither the control channel or the next scheduled data transmission toUE2 from UE1. The control channel PSCCH may be prioritized since thenext scheduled data transmission by UE1 is not known. However, the datachannel PSSCH is not precluded.

This is depicted in FIG. 8, where the case is shown in which the HARQfeedback (for example, a feedback signaling whether an information unithas been properly received or not, also designated as ACK/NACK feedback)is transmitted via sidelink. UE2 transmits data using a unicast sidelinktransmission 810, as depicted by the left arrow pointing from UE2 toUE1. The sidelink unicast transmission 810 may comprise a controlchannel PSCCH and a data channel PSSCH. After UE1 has received thetransmission, it sends back appropriate HARQ feedback information, asdepicted by the right hand arrow 820 pointing from UE1 to UE2. The HARQfeedback may be signaled using a check value that has been appropriatelyamended according to whether or not the information from UE2 has beenproperly received or not. This feedback may be embedded into controlinformation, e.g. the PSCCH only, the data channel PSSCH is not used. Inanother scenario, the control information PSCCH is not used, but thefeedback is embedded into the data channel PSSCH. In a furtheralternative, the feedback is embedded into both control informationPSCCH and data PSSCH.

Regarding FIG. 8, in other words, three different ways are illustratedin which the HARQ feedback can be piggybacked on existing control anddata channels of the sidelink. In the first and second options, the HARQare transmitted on the checksum of the control and data channelrespectively. The third option is not precluded but entails doubling theblind decoding effort to extract the HARQ information. This could beapplicable to out of coverage, autonomous, mode of D2D/V2X transmissionsas well, which is also known as mode 2/mode 4, respectively.

B) The uplink HARQ feedback transmissions are relayed via the basestation, e.g. gNB, to UE1, which is then relayed to UE2. This is shownin FIG. 9.

FIG. 9 shows the case in which the HARQ feedback is transmitted viauplink/downlink, it presents an alternative method to convey the CRCembedded HARQ feedback to UE 2, i.e. via the uplink through the basestation (eNB/gNB). The uplink control and data channels are used toprovide the HARQ indications, in the case that the SL of UE 1-UE 2 isunavailable/weak or not scheduled for any transmissions. In detail, UE2transmits data using a unicast sidelink transmission, as depicted by thearrow 910 pointing from UE2 to UE1. The sidelink unicast transmission910 may comprise a control channel PSCCH and a data channel PSSCH. AfterUE1 has received the transmission 910, it sends back appropriate HARQfeedback information, as depicted by the arrow 920 pointing from UE1 toa base station, e.g. gNB. The HARQ feedback may be signaled using acheck value that has been appropriately amended according to whether ornot the information from UE2 has been properly received or not by UE1.This feedback may be embedded into control information of the uplink,e.g. the PUCCH only, the data channel PUSCH is not used. In anotherscenario, the control information PUCCH is not used, but the feedback isembedded into the uplink data channel PUSCH. In a further alternative,the feedback is embedded into both uplink control information PUCCH anddata PUSCH. The gNB then forwards an indication whether a retransmissionis needed or not using the downlink 930 to UE2.

In other words, FIG. 9 shows that, according to an embodiment, the HARQfeedback may be sent (or forwarded) via a base station. Thecommunication may proceed as follows. First, a data transmission is sentfrom UE2 to UE1, this transmission may be made via a sidelink unicastconnection 910. For this transmission, a control channel PSCCH and adata channel PSSCH may be used. After the transmission, UE1 amends acheck value associated with the data transmission so as to contain HARQfeedback information. This HARQ feedback information may be sent to thebase station gNB. In a first embodiment, the control channel PUCCH maycontain the checksum including the HARQ feedback. In another embodiment,the checksum including the HARQ feedback may be sent using the datachannel PUSCH. In a third embodiment, the checksum with the HARQinformation may be sent by both the control and data channels PUCCH andPUSCH. Hence, the embodiment according to FIG. 9 presents an alternativemethod to convey the CRC embedded HARQ feedback to UE2, i.e., via theuplink through the base station. The uplink control and data channelsare used to provide the HARQ indications, for example in the case thatthe sidelink of UE1 to UE2 is unavailable/weak or not scheduled for anytransmissions.

In both cases, the idea is to embed the HARQ feedback into a checkvalue, e.g. a CRC, of a control channel transmission or subsequentscheduled data transmission from UE1, such that UE2 or the base stationcan, for example, employ blind decoding to extract its own HARQ feedback(e.g. a HARQ feedback intended for the respective communication device)in order to initiate a decision on whether to perform a retransmissionor not.

An advantage of embedding the HARQ feedback into the check value (e.g.CRC) is that the control information/data does not need to be decoded todetermine a HARQ-ACK information, but rather, from the outcome of thecheck value. For example, the checksum may be a cyclic redundancy check,CRC value. The check value will then serve two purposes:

-   -   i) Serve as an error detection mechanism to preserve the        integrity of the transmitted control or data information;    -   ii) Indicate whether a retransmission is needed via an        additional ACK/NACK indication.

In this case, one or more additional bits would in some cases have to beincluded into the checksum. But in this case, support for legacy usersmay be at risk of exclusion with such an amended checksum format. Thus,inclusion of more bits into the checksum should be considered as beingoptional.

In order to more clearly illustrate an example of the feedbacktransmission, embedding and extraction, FIG. 10 shows a timeline of theHARQ procedure. In a first step, UE2 sends a transmission 100 to UE1.This transmission comprises control information as well as a data. Boththe control information 101 and the data 103 comprise each a respectivechecksum 102 and 104, control information 101 comprises the checksum102, the data 103 comprises checksum 104. UE1 determines as to whetheror not the transmission has been properly received. Based on thisdetermination, a checksum of another transmission 109 may be altered. Asdepicted in FIG. 10, UE1 sends a transmission 109 to UE2, thistransmission comprises control information 105 with checksum 106 anddata 107 with checksum 108. In this particular case, the checksum 108 ofthe data 107 is altered (when compared to an original check sum, or whencompared to a check sum which would be transmitted for the same data fora different outcome of the determination) in order to reflect theoutcome of the determination. For signaling this outcome, UE1 sendscontrol information 105 together with its checksum 106, and data 107together with the altered checksum 108 to UE2. It is apparent that thealteration of the checksum of the data is merely an example, and insteadof this checksum 108, also the checksum of the control information 106or even both checksums 106 and 108 could have been altered.

Accordingly, UE1 can conclude on the basis of a common evaluation of thedata 107 and the (altered) checksum 108 whether the transmission 100 wasproperly received by UE2.

FIG. 11 shows a conceptual block diagram of the steps performed by thetransmitter and receiver. For example, the functionality shown atreference numerals 1100 to 1130 may be performed by UE1 (for example asshown in FIG. 8 or in FIG. 9 or in FIG. 10) and the functionality shownat reference numerals 1140 to 1190 may be performed by UE2 (for exampleas shown in FIG. 8 or in FIG. 9 or in FIG. 10).

Initially, data to be transmitted (for example from UE2 to UE1 depictedin FIG. 10) is provided. In a first step 1100, a checksum of the data iscomputed. As mentioned before the checksum may be in embodiments acyclic redundancy check CRC value, but it is apparent for the personskilled in the art that also other checksums (advantageously multi-bitchecksums) are possible like the so-called longitudinal parity check,Fletcher's checksum or the like. Further, based on whether or not aprevious data packet (for example, transmitted in transmission 810 or910) has been received properly or not, a mask is selected in step 1105,and this mask is used for amending the checksum value. In step 1110, thecomputed CRC value is amended based on the selected mask. In thisillustrative case, an XOR operation is performed on the checksum. Themask used for the XOR operation may be ‘1100’ for ACK and ‘0011’ forNACK in the illustrative case that the checksum has the length of fourbits. It is clear that any other combination of masks can be used, andthat the size of the mask has to be adapted to the size of the computedchecksum. After performing the XOR operation, the checksum is attachedto the data in step 1120. In step 1130, the information comprising thedata as well as the attached checksum are channel coded and transmitted(for example, in transmission 820 or 920).

The receiver (for example, UE2 or gNB) receives the information andperforms a channel decoding in step 1140. In the next step, theinformation is broken down into the checksum and the data in step 1150.The detached checksum is subjected to an XOR operation, whereby thechecksum is XORed with the masks corresponding to ACK and NACK in step1160. The extracted data is used to perform the computation of thechecksum, in this case a CRC, in step 1170. In step 1180, the computedchecksum is compared to the checksums that have been detached from theinformation and subjected to the XOR operations to determine whether thereceived information comprised a checksum amended by a maskcorresponding to ACK or by a mask corresponding NACK. Based on theresult of the comparison, it is determined in step 1190 whether an ACKor a NACK case is present. In the case of ACK, it is found that thepreviously transmitted data (for example, transmitted by UE2) has beenreceived properly (for example, by UE1) and no retransmission isnecessary. In the case that a NACK is determined, a retransmission maybe triggered. In the case that the computed checksum (computed in step1170) neither corresponds to the checksum amended with the maskcorresponding to ACK nor with checksum amended with the maskcorresponding to NACK, it can be concluded, by the communication deviceUE2, that the data transmitted from UE1 to UE2 (for example, datetransmitted with transmission 820 or with transmission 920, or data 107)have been corrupted. In the latter case, it is typically not possible todetermine whether data transmitted from UE2 to UE1 with transmission 810or with transmission 910 (for example, data 103) has been properlyreceived by UE1. Accordingly, in a conservative approach,re-transmission may also be made in this case.

FIG. 12 illustrates an example in which an ACK indication is to be sentin a system corresponding to the block diagram of FIG. 11. As anexample, the checksum, e.g. a CRC, computed in step 1200, is ‘1111’. Themasks for step 1205 are ‘1100’ for an ACK and ‘0011’ for a NACK. Hence,in order to signal an ACK, the ‘1100’ mask is used in step 1210. Theresult of XOR in the checksum ‘1111’ with the mask ‘1100’ is ‘0011’. TheXOR result is attached to the data in step 1220 and channel coded instep 1230. After transmission, the receiver decodes the informationinstep 1240 and detaches in step 1250 the checksum which is in thisexample ‘0011’. Thereafter, an XOR operation is performed in step 1260on the checksum with both the masks values ‘1100’ and ‘0011’. Therespective outcomes are ‘1111’ and ‘0000’. These two outcomes arecompared in step 1280 to a checksum that has been calculated in step1270 based on the decoded data with the result ‘1111’. A comparison ofthe values yields that an ACK has been conveyed. Hence, in step 1290, itcan be determined that an ACK has been transmitted and that a previouslytransmitted data has been properly received.

In the following, different embodiments are presented that provide aHARQ signaling according to the principles discussed above. It should benoted that any of the details mentioned above may optionally beintroduced into the embodiments described in the following, eitherindividually or in combination.

FIG. 1 shows a communication device 150 in accordance with an embodimentof the present application. A communication device, UE1, is receivingone or more information units 160, which may be data blocks or packetsor also control blocks or packets from a second communication device(e.g. from UE2). The communication devices may, for example, be mobilecommunication devices like user equipments, or, in a general case,cellular phones, tablets, PDAs, wearables, IoT devices or any othercommunication device that is communicating with other communicationdevices. The communication device performs a check as to whether theinformation unit has been properly received. There exists differenttechniques for checking whether an information has been properlyreceived, one of these tests may be using a check sum such as a cyclicredundancy check, longitudinal parity check, Fletcher's checksum or thelike. Based on the result of the determination whether the informationunit has been properly received, the communication device UE1 amends acheck value 180 associated to an information unit 170 to be transmittedby the communication device UE1. This information unit has associated acheck value 180, this check value is selectively amended so as toreflect the result of the determination whether the information unit hasbeen properly received. After the check value has been amended, theinformation unit with the amended check value 172 is transmitted. Withthis technique, a signaling has been established that can be used tosignal to the receiving communication device whether or not a previousinformation unit has been properly received or not.

The check value 172, that is amended as described above, may allow forthe detection of one or more bit errors after reception of theinformation unit 170, and depending on the kind of check value, biterrors at least up to a predetermined number of bit errors can bedetected, and in cases depending on the check value used, even thecorrection of bit errors is possible.

The signaling as to whether the information unit 160 has been properlyreceived may, for example, be performed using a particular manipulationof the check value associated with an information unit 170. For example,this amending may comprise performing an XOR operation with anappropriate bit mask. In the case that the information has been properlyreceived, and acknowledgement is to be signaled, usually referred to asACK. This ACK may be signaled by using a bit mask of a number of ‘0’ s,which would leave the original check value unchanged. In the other case,that it has to be signaled that the information unit 160 has not beenproperly received, a non-acknowledgement, NACK, has to be signaled. Forsignaling a NACK, a bit mask consisting of a number of ‘1’ s may beused, which inverts the original check value when applying the XORoperation.

This kind of feedback, also referred to HARQ feedback, can bepiggybacked on control or data channels. The communication device UE1shown in FIG. 1 may, for example, correspond to UE1 shown e.g. in FIG.8, and it is depicted in FIG. 8 that the HARQ feedback can bepiggybacked onto an information unit transmitted in a control channelPSCCH, can also be transmitted in a data channel PSSCH and can also beboth transmitted in control and data channels PSCCH and PSSCH. Whileusing only one channel for piggybacking this information may help tosave the computational effort, piggybacking the information to bothcontrol and data channel increases the reliability of the signalingprocess.

FIG. 2 shows a conceptual drawing of the communication device UE2 200.As described in relation to FIG. 1, also the communication device UE2200 may be a mobile communication device, for example, a user equipmentor the like. Communication device UE2 200 transmits one or moreinformation units 210 to another communication device, which may be forexample UE1. The communication may be performed directly via a sidelinkconnection, in this case, a base station does not need to be involved inthe communication process. Also here, the information units may be datablocks or packets, or may also be control blocks or packets. Thiscommunication device receives 220 one or more information units havingassociated one or more check values 222. These check values 222 may bemultibit binary values like for example, CRC values. Based on the checkvalues 222, the communication device 200 derives (block 202) whether theinformation units 210 that have been previously transmitted, have beenproperly received by the other communication device.

As described above, the check value 222 may be used for detecting biterrors up to a certain number of bit errors, and also may be in casesused for correction of these bit errors. Based on the check value 222,the communication device UE2 200 may determine whether or not apreviously transmitted information unit has been properly received ornot using a number of predetermined derivation rules. If a singleACK/NACK condition is to be signaled, there may be two predeterminedderivation rules, but it is also possible to signal a different numberof ACK/NACK states, then an appropriate number of derivation rules hasto be used. If for example not two but four or six acknowledgementconditions have to be signaled, four or six derivation rules may beused. The derivation may be performed using the check sum 222 receivedwith the information unit 220, namely by comparing the received checksum 222 with a check sum that is calculated by the communication deviceUE2 based on the information unit. In case that an XOR operation isused, the communication device may perform the same XOR operation on thecalculated check sum and compare the result to the received check sum222. By this comparison, it can be determined which particular kind ofbit mask has been used to alter the check sum which allows to concludewhether an ACK or a NACK is intended to be signaled.

FIG. 3 shows a conceptual drawing of a further communication device 300according to the present application. This communication device may be anetwork node or a base station, for example a gNB. The communicationdevice 300 receives one or more information units 310 having associatedone or more check values 312 e.g. from a first communication device(e.g. from the communication device 150, UE1). The communication device300 determines (block 302) whether the one or more check values 312correspond with a respective information unit (or, to be precise, with auseful data content of the respective information unit), that may havebeen previously transmitted, according to a first predeterminedderivation rule or according to a second predetermined derivation ruleor do not correspond with the respective information unit at all. Thecommunication device 300 initiates a retransmission of a correspondinginformation unit to the first communication device UE1 in dependence onthe determination (for example using an appropriate message orinformation unit 320), e.g. in the case that it is determined that thepreviously transmitted information unit has not been properly received(by UE1).

As shown in FIG. 3, the information unit 310 received by thecommunication device 300 has associated a check value 312, thisinformation unit may be transmitted from another communication device,e.g., UE1. The information may be control information in a PUCCH or datain a PUSCH. As mentioned before, it is possible to use controlinformation or data information (or, more precisely, a check valueassociated with the control information or a check value associated withthe data) for conveying the ACK/NACK signaling, but it is also possibleto use both the control and data channel (or, more precisely, checkvalues associated with the control and data channels) in parallel inorder to increase reliability of the signaling. As mentioned before, thecheck value 312 may be a cyclic redundancy check value or any othervalue created according to any type of check. The check value may helpto identify bit errors up to a certain number of bit errors, and mayeven help to correct bit errors.

FIG. 4 shows the conceptual layout of a system 400 comprising acommunication device 410 according to FIG. 3 serving as a base station,a communication device 420 according to FIG. 2 serving as a data sendercommunication device and a communication device 430 according to FIG. 1,which serves as a data receiver communication device. The data sendercommunication device 420 transmits one or more information units 422directly to the data receiver communication device 430 via a sidelinkconnection. The data receiver communication device 430 piggybacks (block434) an acknowledgement information, signaling whether an informationunit has been properly received from the data sender communicationdevice or not, in a check value information 432.

This check value information 432 may be transmitted to the data sendercommunication device 420, along with a respective information unit 440,directly, or may be sent to the communication device 410 which serves asa base station.

FIG. 5 shows a flow chart of a method, e.g. for the communication deviceof FIG. 1. In a first step 500, the communication device (e.g. UE1)receives one or more information units from a second communicationdevice (e.g. UE2). These information units may, for example, be receivedvia a direct link, such as a sidelink. As mentioned above, theinformation units may be data blocks or packets, or may also be controlblocks or packets. In step 510, it is shown that a check value isamended, the check value is associated with an information unittransmitted by the communication device, and may be transmitted to abase station, gNB for example, or to the second user equipment, UE2. Thecheck value is amended in dependence on whether the information unitreceived from the second communication device UE2 has been properlyreceived by the communication device UE1 or not, to thereby provide asignaling whether the information unit received from the secondcommunication device UE2 has been properly received or not. Thissignaling may be performed as mentioned before, for example byperforming an XOR operation on the check value using an appropriate bitmask.

FIG. 6 shows a method, e.g. for a communication device according to FIG.2. In step 600, the communication device UE2 transmits one or moreinformation units, e.g., via a sidelink, to another communication deviceUE1. When for example, the information units are transmitted via asidelink, this may not involve a base station, to which thecommunication device UE2 could also communicate. In step 610, thecommunication device UE2 receives one or more information units havingassociated one or more check values. These check values may be multibitbinary values, such as the CRC values mentioned before. As mentionedabove, also other check values are possible. In step 620, thecommunication device UE2 derives an information indicating whether theone or more information units transmitted by the communication deviceUE2 have been properly received by the other communication device UE1 ornot in dependence on the one or more check values. This deriving may beperformed using certain rules, like the before mentioned rules applyingto XOR operations performed on the one or more check values.

FIG. 7 shows a method for communication, e.g. for a communication deviceshown in FIG. 3. In step 700, the communication device BS receives oneor more information units having associated one or more check values,from a first communication device UE1. In step 710, the communicationdevice BS determines whether the one or more check values correspondwith a respective information unit according a first predeterminedderivation rule, or according to a second predetermined derivation rule,or do not correspond with the respective information unit. The firstpredetermined derivation rule may refer to the case that a NACKcondition is to be signaled, and the second derivation rule may be usedfor signaling an ACK condition. In step 720, the communication device BSinitiates a retransmission of an information unit to the firstcommunication device UE1 in dependence on the result of thedetermination. For example, the retransmission may be initiateddepending on whether the one or more check values correspond with arespective information unit according to a first predeterminedderivation rule or according to the second predetermined derivationrule, or whether they do not correspond with the respective informationunit at all.

Unused Transmission Resource Pools for Feedback Transmission

Further embodiments also address the transmission of feedbackinformation.

According to these embodiments, unused resource blocks are, for example,detected by a mobile communication device, for example UE1 known fromFIGS. 1-3. For example, user equipment UE1 listens to a resource (forexample, monitors one or more wireless resource units) for detectingunused resource block pools (or unused wireless resource units). If suchan unused resource block pool is found by UE1, the feedback istransmitted on this empty resource.

For example, congestion control in vehicle to everything, V2X, may beperformed according to these embodiments by detecting if a physicalresource is used by other V2V user equipment in order preventcollisions. For example, in some embodiments a mechanism which is(substantially) identical to congestion control used invehicle-to-everything-communication may be used to detect an unused (orat least partially unused) wireless resource. The CR is one of themetrics used to determine the occupancy of a physical resource.

FIG. 20 illustrates the concept of the “listen before transmit” feedbackmechanism according to an aspect of the present application. It enablesunused scheduled resources of other UEs to be used for sidelinkfeedback.

In other words, UE1 initially senses the occupancy of UE B (or UE2, oranother communication device) on the first part of the subframe (i.e.determines whether UE2 transmits in the first part of the subframe),before transmitting its feedback information on the second part of thesubframe. If UE1 detects the “absence” of UE B (or UE2, or anothercommunication device), then the feedback may be transmitted (by UE1)using the resource. It is apparent that the feedback is not limited toonly HARQ, but can also include CQI and/or RI and/or PMI, for example inthe future likelihood MIMO D2D/V2X unicast transmissions.

In some embodiments, a technique is optionally provided that allows thefeedback receiving UE to know which resources to search for this type ofdynamic feedback transmission.

FIG. 13 shows an illustrative communication device 1300 according to thepresent application, which may be a user equipment UE1, that receivesone or more information units 1310, which may be data blocks or packetsor control blocks or packets, from a second communication device, forexample, user equipment UE2. These information units 1310 may bereceived via a direct link. Communication device UE1 generates afeedback information 1312, which may for example be an acknowledgementmessage. It is also possible that the feedback information 1312 is (orcomprises) a channel quality indicator, and/or a rank indicator, and/ora precoding matrix indicator and/or channel state information. Thisfeedback information 1312 is then transmitted (by an appropriate signal1320) in a wireless resource unit, e.g., of a resource block pool ortransmission resource pool 1330, that is reserved (e.g. preferentiallyor prior-rankingly) for a transmission of a different communicationdevice but is not used or only partly used. The resource block pool1330, which may be a transmission resource pool, is explained in greaterdetail in connection with FIGS. 20 and 21. In general, such atransmission resource pool 1330 comprises portions (e.g. wirelessresource units) that may be reserved, that means allocated or scheduledby a base station for a certain communication device (or forpreferential use by the certain communication device). In situationswhere a part 1332 of the transmission resource pool 1330, a wirelessresource unit, is reserved for a communication device (or forpreferential use by the communication device), but not used or onlypartly used by this communication device, it is possible that the unusedpart 1332 of the transmission resource pool 1330, namely the unusedwireless resource unit, is used for transmitting the above mentionedfeedback information. In this regard, FIG. 13 shows that the feedbackinformation 1312 is inserted by the communication device 1300 into anunused part of the transmission resource pool 1330 (even though thispart is reserved or allocated for preferential use by anothercommunication device).

FIG. 14 shows another embodiment following this concept, namely that acommunication device 1400, which may be user equipment UE2, transmitsinformation units 1410 to other communication devices, for example, userequipment 1420, e.g. UE1. This transmission may be performed directlyvia a sidelink. Communication device 1400 monitors a resource unit 1442,which may be a wireless resource unit. This resource unit 1442 may be apart of a transmission resource pool 1440, and this wireless resourceunit 1442 is not allocated to the other communication device, e.g., UE1,but reserved for a different communication device (or reserved forpreferential use by the different communication device). The monitoringcomprises monitoring 1430 the resource unit for feedback informationfrom the other communication device (even though the resource unit isreserved for preferential use by the different communication device).Using this technique, feedback information can be transmitted to thecommunication device 1400 using a resource unit 1442 that is unused orat least partly unused.

FIG. 15 shows a further embodiment according to the present application,where a communication device 1500, which may be a base station BS,coordinates 1510 a resource allocation, e.g., of the resources of atransmission resource pool, TRP, 1520. Communication device 1500communicates with communication devices 1540 for which the communicationdevice 1500 has coordinated the resource allocation. The communicationdevice 1500 provides a resource allocation information 1502 to thesecommunication devices 1540, wherein the resource allocation information1502 describes an allocation of wireless communication resources todifferent communication devices and indicates which wirelesscommunication resources are useable for a transmission of feedbackinformation by other communication devices 1540. In particular,communication device 1500 may for example signal that wirelesscommunication resources which are reserved for preferential use by agiven communication device are also usable for a signaling by othercommunication devices which are different from the given communicationdevice. In this manner, the communication device 1500 may authorize—byan appropriate signaling—a lower-ranking usage of wireless communicationresources for signaling if these communication resources are not used bythe devices which are scheduled as prior-ranking users of the respectivewireless communication resources.

FIG. 16 shows a conceptual arrangement of a system 1600 comprising acommunication device 1610 serving as a base station (for example havingthe functionality of the base station 1500 as described with referenceto FIG. 15), a communication device 1620 serving as a data sendercommunication device (for example, having the functionality of thecommunication device 1400 as described with reference to FIG. 14), and acommunication device 1630 acting a data receiver communication device(for example, having the functionality of the communication device 1300as described with reference to FIG. 13). The data sender communicationdevice 1620, for example, UE2, transmits one or more data units 1622directly to the data receiver communication device 1630, e.g., UE1, viaa sidelink. The data receiver communication device 1630 transmits anacknowledgement information 1632 that signals whether the informationunit has been properly received or not. Here, data receivercommunication device 1630 may use a wireless communication resourcereserved for transmission of another wireless communication device forthe signaling.

FIG. 17 shows a flow chart of a method that may be performed by acommunication device, for example by user equipment UE1, e.g. known fromFIG. 13. The method comprises, in step 1710, that one or moreinformation units are received at communication device UE1 from a secondcommunication device, which may be UE2. UE1 then transmits feedbackinformation in a wireless resource unit which is reserved fortransmission of a different communication device but which is not oronly partly used by the different communication device. By thistechnique, unused bandwidth can be used and feedback information can betransmitted without the need of allocating bandwidth to thecommunication device UE1 for transmitting the feedback information.

FIG. 18 shows a method that may be performed by a communication device,for example user equipment UE2, e.g. known from FIG. 14. Communicationdevice UE2 transmits one or more data units to another communicationdevice, which may be UE1, in step 1810. This transmission may beperformed directly via a sidelink, e.g., without involving a basestation. Communication device UE2 monitors in step 1820 a resource unitthat is not allocated to the another communication device, but reservedfor transmission of a different communication device for feedbackinformation from the other communication device. By this way, thecommunication device UE2 monitors for the feedback information and mayextract the feedback information that is destined for this communicationdevice without having to allocate a resource unit for transmitting thisfeedback information.

In FIG. 19, a method is illustrated for a communication device, whichmay be a base station, for example, a gNB, e.g. known from FIG. 15. Thecommunication device BS coordinates in step 1910 the resource allocationof a plurality of communication devices. The communication device BSprovides in step 1920 a resource allocation information corresponding tothe coordinated resource allocation, to the plurality of communicationdevices, wherein the resource allocation information describes anallocation or wireless communication resources to differentcommunication devices and indicates which wireless communicationresources are usable for transmission of feedback information by othercommunication devices.

FIG. 20 shows the structure of a transmission resource pool 2000conceptually, namely an overview of a slot 2010 of a subframe. The slot2010 is allocated for sidelink communications. In this particularexample, the resources 2020 (for example, one or more groups offrequency ranges of a time-frequency grid, or one or more groups oforthogonal codes; generally speaking one or more blocks of wirelessresource units 2022) scheduled for use by user equipment B may becompletely unused, depicted by label ‘unused portion’ 2030. This can bedetected by the user equipment 1 listening or sensing the respectiveresource.

When it is sensed (e.g. by UE1) that the resource is unused, userequipment 1 uses the unused resource for feedback transmission. Forexample, a first part (or a first half) of the respective wirelessresource units (for example, one or more sTTIs in an initial part of a5G communication frame) may be used as a sensing period. In other words,UE1 may, for example, listen to the first or initial part of a wirelessresource unit (for example, of a wireless resource unit allocated toanother device for prior-ranking use, and signaled as being usable forsignaling in a lower-ranking manner), and may transmit a signalinginformation in a later part (for example, in a second part or in asecond half) of said wireless resource unit if the listening or“sensing” performed in the first part indicated a non-usage of thewireless resource unit.

FIG. 21 shows a conceptual overview over the structure of a transmissionresource pool 2100. As apparent from FIG. 21, the transmission resourcepool 2100 is part of a subframe, in this case it is belonging to a slot2110 allocated for sidelink communications. A part 2130 of thetransmission resource pool (which may, for example, comprise multiplenon-contiguous resource regions) is scheduled for user equipment UE A,the other part 2120 (which may, for example, comprise multiplenon-contiguous resource regions) is scheduled for user equipment UE B.The part scheduled for UE B is not fully used by UE B, there are usedportions 2122, but there are also unused portions 2124. A further userequipment, for example, UE1 performs a sensing/listening for such unusedportions 2124. When UE1 has feedback information to be transmitted, forexample HARQ feedback information or CSI information, the unusedportions 2124 of the TRP 2100 may be used for transmitting this feedbackinformation.

Again, in other words, according to an embodiment, e.g. as shown FIG.20, it may be possible to search all resource block pools that aretotally, i.e., 100% unused by UE B. As an example, resource block poolsthat are totally (100%) unused by UE B or by any other UE may bedesignated by the wording “unused portion” as shown in FIG. 20. Inanother embodiment, e.g. as shown in FIG. 21, it is not required thatthe resource block pools are totally unused, but also partially unusedresource block pools are searched for. This is depicted in FIG. 21 whereit is shown that a part of the transmission resource pool is used by UEB. Like in FIG. 20, UE1 performs sensing/listening and transmitsfeedback information like HARQ feedback or CSI on the detected unusedportion of the resource.

The transmission resource pool shown in FIGS. 20 and 21 may, forexample, be a physical resource block, PRB (e.g. of a 5G communicationsystem).

In another embodiment, the UE receiving feedback may not search/senseall allocated reception pools (or all possible resources). For example,a rule can be devised at the UE transmitting the feedback and the UEreceiving the feedback (wherein the “rule” may, for example be providedby the base station, for example in the form of a signaling of resourcesusable for signaling). As an example, this rule may include (for examplea signaling) where the feedback is included and where it is to besearched for the feedback. For example, a signaling from a managingcommunication device may indicate which wireless resource units areusable for feedback.

According to an optional aspect of the present application, in order forthe receiving UE, i.e., UE2 to dynamically detect the transmittedfeedback from UE1, the base station may allocate this UE specific searchspace for the feedback to UE2. This may avoid the overhead for thefeedback-receiving UE to blindly detect (or search) all sidelinkresources for the feedback from UE1. The base station can allocate thisUE specific search space according to the traffic or utilization of theresources, e.g., if certain aperiodic ultra-reliable low latency URLLCsidelink traffic is only used by 60% of the time compared to theperiodic sidelink resources which are used 95% of the time, the basestation would appropriately define the UE specific search space to be inthe URLLC sidelink resources. The feedback receiving UE will search onlythe subset of resources relating to URLLC sidelink traffic. This mayhelp to reduce the overhead and hence help to reduce the CPU load.

As mentioned before, for example, the allocation may also includeresource block pools that are partially used by UE B.

In embodiments, unused PC5 resources may be used for one of thefollowing:

-   -   transmitting HARQ feedback on PC5    -   by listening on a first part of a subframe if this part is being        used, and, if the first part not used, the second part of the        subframe is used for transmitting the feedback. This mechanism        may be used for HARQ or CSI reporting, any combination of sTTI        or mini-slots. (It is noted that a similar mechanism has been        mentioned in V2X and could optionally be used in embodiments        according to the present invention. Transmission in the second        part might cause problems to the automatic gain control, AGC, of        legacy UEs, but devices used in the Internet of Things, IoT,        might not have an AGC)    -   transmitting the embedded transmission of the feedback within        the resource block pools for both the PSCCH and PSSCH in        conjunction with the subframe bitmap may be examined and        considered.

Bundled Broadcast HARQ to Multiple Transmitting UEs (D2D/V2X BundledHARQ)

In the following, some other embodiments according to aspects of theinvention will be described.

It is of course also possible that a communication device performs adevice-to-device communication with many other communication devices. Inthis case, the device receiving multiple unicast transmission from othercommunication devices has to provides feedback information, like theHARQ feedback mentioned before, to the other communication devices.

FIG. 22 shows a conceptual drawing of a communication device 2200, forexample, user equipment UE1 that receives one or more information units2222 from a plurality of other communication devices 2220. Theseinformation units 2222 may be received via direct link without aninvolvement of a base station. Communication device 2200 receives aresource allocation message 2212 from a managing communication device2210, which may be a base station BS. The resource allocation message2212 defines an allocation of bit positions associated with anacknowledgment of information units received (e.g. by UE1) from theplurality of other communication devices 2220 in a combinedacknowledgement information unit 2202. The communication device 2200transmits such a combined acknowledgement information unit 2202 inresponse to the reception of the information units 2222 from theplurality of other communication devices 2220 using the allocation ofbit positions defined in the resource allocation message. In this way,communication device 2200 can provide feedback information to the othercommunication devices 2220 from which it has received the informationunits 2222, and can signal in this way whether or not the informationunits have been properly received or not, for example. The communicationdevice 2200 may, optionally, be supplemented by and of the features andfunctionalities described herein, either individually or in combination.

FIG. 23 shows a communication device 2300, which may be a user equipmentof a plurality of user equipments. The communication device 2300, forexample, a user equipment, e.g. UE2, transmits one or more informationunits 2310 to another communication device 2340, which may be userequipment UE1, for example directly via a sidelink without involving abase station. Communication device 2300 receives a resource allocationmessage 2330 from a managing communication device 2350, e.g. a basestation BS, the resource allocation message defining an allocation ofbit positions associated with an acknowledgement of information unitsreceived by the other communication device UE1 in a combinedacknowledgement information unit. Communication device UE2 receives sucha combined acknowledgement information unit 2320 and evaluates (box2302) a bit at a bit position defined by the resource allocation message2330 to derive an information whether one or more information unitstransmitted by the communication device 2300 have been properly receivedby the other communication device 2340 or not. In this way, an efficientsignaling of feedback information is provided. The communication device2300 may, optionally, be supplemented by and of the features andfunctionalities described herein, either individually or in combination.

FIG. 24 shows a conceptual communication device 2400 which may be thebefore mentioned managing communication device, e.g., a base station BSof FIGS. 22 and 23. Communication device 2400 coordinates (box 2402) theresource allocation of resources to a plurality of communication devices2420, and communicates with this plurality of communication devices.Communication device 2400 provides a resource allocation information2410 to the plurality of communication devices 2420, the resourceallocation information 2410 defining an allocation of bit positionsassociated with an acknowledgement of information units received by agiven communication device, e.g., UE1, from a plurality of othercommunication devices 2420, e.g., UE2 to UEN, in a combinedacknowledgement information unit to be transmitted in response to thereception of information units from the plurality of other communicationdevices 2420. The communication device 2400 may, optionally, besupplemented by and of the features and functionalities describedherein, either individually or in combination.

FIG. 25 shows an illustrative method for a communication device, forexample user equipment UE1 of FIG. 22. In step 2510, one or moreinformation units are received from other communication devices, e.g.,UE2 to UEN, the reception may be performed via direct links.Communication device UE1 receives a resource allocation message from amanaging communication device, which may be communication device BS. Theresource allocation message defines an allocation of bit positions in acombined acknowledgement information unit, the bit positions beingassociated with an acknowledgement of information units received fromthe plurality of other communication devices. Communication device UE1transmits a combined acknowledgement information unit using theallocation of bit positions defined in the resource allocation message.In this way, a signaling of feedback information to the othercommunication devices is provided.

FIG. 26 provides a method for a communication device, for example userequipment UE2 of FIG. 23, of a plurality of user equipments, thattransmits one or more information units to another communication device,for example, user equipment UE1. Communication device UE2 receives aresource allocation message from a managing communication device, themanaging communication device may be a base station. The resourceallocation message defines the allocation of bit positions in a combinedacknowledgement information unit as described above. Communicationdevice UE2 receives a combined acknowledgement information unit, andevaluates a bit at a bit position defined by the resource allocationmessage in order to derive an information whether the one or moreinformation units have been properly received by the other communicationdevice or not.

FIG. 27 shows a method for a communication device, which may be amanaging communication device e.g. the base station BS of FIG. 24.Communication device BS coordinates the allocation of resources to aplurality of communication devices. The communication device BS providesa resource allocation information to the plurality of communicationdevices, the resource allocation information defines the allocation ofbit positions associated with an acknowledgement of information unitsreceived by a given communication device in a combined acknowledgementinformation unit to be transmitted in response to the reception ofinformation units.

FIG. 28 show a conceptual overview of a system 2800 comprising aplurality of communication devices, the communication devices being userequipments UE1 to UE5 and a base station gNB (which may, for examplecorrespond to communication device 2400 mentioned above). Communicationdevice UE1 (which may, for example correspond to communication device2200 mentioned above) receives multiple data transmissions 2810 fromuser equipments UE2 to UE5 (which may, for example correspond tocommunication device 2300 mentioned above) and also provides multiplefeedback transmissions 2820 as a broadcast sidelink HARQ feedback. Forproviding this feedback, the combined acknowledgement information unitas described above is used.

In the following, some alternative embodiments according to theinvention and further details will be described.

A mobile communication device, like UE1 shown in FIG. 28, which isenabled to perform D2D or V2X, is expected to receive multiple unicasttransmissions from a number of transmitting UEs depending on the numberof allocated reception pools. In effect, single, multiple, transferblocks, TBs, from different UEs which each need a feedback like the HARQfeedback discussed above. In order to provide such feedback, anasynchronous and adaptive approach for scheduling the HARQ feedbacktransmissions of multiple transmitting UEs is desired. Currently, thereceiver processing time of a UE is approximately 3 ms, making the nextpossible transmission of feedback at n+4 subframes, where the n^(th)subframe contained the original transmission.

According to an aspect of the application, in the case of high latencyapplications, UE1 can consider the broadcast of its feedback 2820 tomultiple UEs in its vicinity like UE2 to UE5 shown in FIG. 28. FIG. 28shows a system comprising five communication devices UE1 to UE5, whichperform sidelink communications. A base station, gNB, is also depictedbut does not participate in the communication among the mobile devices.This does not necessarily mean that the base station may be notnecessary for this system, because some functionalities, like resourceallocation, may be performed by the base station. The transmitting UEs,that means UEs 2-5, may, for example, blindly decode their respectivefeedback from the bundled feedback using UE-specific scramblingsequences. However, this is not essential. Furthermore, if all or mostof the initial unicast transmissions 2810 from UEs 2-5 occur within acertain time interval, according to an embodiment, it would bebeneficial from UE1's perspective, in terms of feedback overhead tobroadcast it in a bundled fashion to the surrounding UEs. According toan aspect, there may be a content and resource allocation of broadcastmessages, for example, defined in a resource allocation information.

In the following, a resource allocation for a HARQ broadcast message isdiscussed. There are two scenarios.

In scenario 1, possible resource allocation mechanisms and possiblebroadcast message structures which can be used in embodiments of theinvention of the application are described. A base station multicaststhe HARQ resource allocation, HARQ bit position, message size and so onvia a group DCI. This may be a new DCI format. This information ismulticast/groupcast to all UEs for the transmission and reception of theHARQ broadcast message. The base station, for example, includes thefollowing elements in the multicast/groupcast control message:

-   -   a. sidelink transmission resources for which to transmit the        broadcast HARQ feedback message for UE1, and/or    -   b. sidelink reception pool resources for which to receive the        broadcast HARQ feedback message from UE1 and/or    -   c. HARQ bit position information for each HARQ feedback based on        the transmissions received from the UE2 to UE5. FIG. 29 shows an        illustrative structure and/or    -   d. message size of aggregated HARQ feedback, which depends on        the number of UEs that have transmitted to UE1 within a short        period.

FIG. 29 shows an illustrative scenario for an HARQ broadcast feedbackresource allocation and message structure. In this example, a groupmulticast/groupcast HARQ resource allocation is shown. The resourceallocation is transmitted in control information. The base station 2910may transmit this information to the user equipment of user equipments2920. The information indicates the resource that can be expected tocarry the HARQ information and bit positions for each user equipment2920. The HARQ resource may be pre-allocated after UE2-5 havetransmitted.

In other words, FIG. 29 shows option 1 of a group multicast HARQresource allocation. The resource allocation is conveyed in controlinformation to the user equipments 2920. It is indicated which resourceis expected to have HARQ information, and bit positions for each userequipment are indicated. The HARQ resource is (optionally) reallocatedafter user equipments 2-5 have transmitted. User equipment UE1 providesa broadcast/multicast/groupcast feedback message, in this particularcase the broadcast/multicast/groupcast feedback message may comprisefour bits, each bit being assigned to one of the four user equipmentsthat have sent information units to UE1. In the given example, thebroadcast/multicast/groupcast feedback message comprises four bits 1011,this may signal an ACK for UE1, UE4, UE5 and a NACK for UE3.

In scenario 2 depicted in FIG. 30, the HARQ resource allocation, HARQbit positions and message size will be included in the existing DCI 5,downlink control signaling, by base station 3010 for each UE beforeinitial data transmission. Each user equipment UE of user equipments3020 would know its own bit position from which to extract its own HARQfeedback from the broadcast/multicast/groupcast HARQ feedback message ofUE1.

In this case, the base station 3010 may pre-allocate resources for theHARQ broadcast/multicast/groupcast message pre-emptively. However, ifonly a subset of UEs 3020 transmit, e.g., only UE2 and UE5, then thefollowing example occurs:

-   -   a. The base station HARQ broadcast allocation message format        would be HARQ_Broadcast={UE2, UE3, UE4, UE5}.    -   b. However, only UE2 and UE5 transmit with both ACK messages,        UE1 broadcasts the message HARQ_Broadcast=0xxx0 or 0xx0. In this        case, ‘x’ refers to unused feedback and result in some overhead        bits.    -   c. Alternatively, if UE1 only broadcasts the short broadcast        HARQ message HARQ_Broadcast=00 corresponding to UE2 and UE5 that        only transmit data, then UE3 would detect feedback having sent        no data and UE5 would not even be able to receive its feedback.        In this case a retransmission would be triggered by UE5 since no        feedback has been received, see FIG. 30.

In this scenario, the data transmission may include HARQ feedback type,for example passed on from the base station. The DCI 5 may include afeedback toggle. This may be passed on to UE1 via piggybacking on thedata. This may be used for feedback. In case of a decoding failure, thewrong HARQ feedback on a wrong position might be used, which may alsolead to a retransmission.

Further Remarks

It should be noted that the embodiments and aspects disclosed herein canalso be used in combination. In other words, any features andfunctionalities described herein with respect to UE1 may be combined inan extended functionality UE1. Similarly, any features andfunctionalities described herein with respect to UE2 to UE5 may becombined in a respective extended functionality communication device.Similarly, any features and functionalities described herein withrespect to a gNB can be combined in an extended functionalitycommunication device or base station.

Also, any of the features and functionalities described herein withrespect to apparatuses can also be included in corresponding methods.

Furthermore, embodiments are defined by the enclosed claims. However,the embodiments described in the claims can be supplemented by any ofthe features and functionalities described herein (in particular, insections ‘Scrambling Feedback with UE Blind Decoding’, ‘Unusedtransmission resource pools for feedback transmission’ and ‘BundledBroadcast/Multicast/Groupcast HARQ to Multiple Transmitting UEs/D2DBundled HARQ/V2X Bundled HARQ’, but also in the general sections),either individually or in combination.

In case of unclear abbreviations, reference is made to the abbreviationsused in the 5G standardization process, and also in furthercommunication standards (like 3GPP, LTE, and so on).

Implementation Alternatives

Although some aspects have been described in the context of anapparatus, it is clear that these aspects also represent a descriptionof the corresponding method, where a block or device corresponds to amethod step or a feature of a method step. Analogously, aspectsdescribed in the context of a method step also represent a descriptionof a corresponding block or item or feature of a correspondingapparatus. Some or all of the method steps may be executed by (or using)a hardware apparatus, like for example, a microprocessor, a programmablecomputer or an electronic circuit. In some embodiments, one or more ofthe most important method steps may be executed by such an apparatus.

Depending on certain implementation requirements, embodiments of theinvention can be implemented in hardware or in software. Theimplementation can be performed using a digital storage medium, forexample a floppy disk, a DVD, a Blu-Ray, a CD, a ROM, a PROM, an EPROM,an EEPROM or a FLASH memory, having electronically readable controlsignals stored thereon, which cooperate (or are capable of cooperating)with a programmable computer system such that the respective method isperformed. Therefore, the digital storage medium may be computerreadable.

Some embodiments according to the invention comprise a data carrierhaving electronically readable control signals, which are capable ofcooperating with a programmable computer system, such that one of themethods described herein is performed.

Generally, embodiments of the present invention can be implemented as acomputer program product with a program code, the program code beingoperative for performing one of the methods when the computer programproduct runs on a computer. The program code may for example be storedon a machine-readable carrier.

Other embodiments comprise the computer program for performing one ofthe methods described herein, stored on a machine-readable carrier.

In other words, an embodiment of the inventive method is, therefore, acomputer program having a program code for performing one of the methodsdescribed herein, when the computer program runs on a computer.

A further embodiment of the inventive methods is, therefore, a datacarrier (or a digital storage medium, or a computer-readable medium)comprising, recorded thereon, the computer program for performing one ofthe methods described herein. The data carrier, the digital storagemedium or the recorded medium are typically tangible and/ornon-transitionary.

A further embodiment of the inventive method is, therefore, a datastream or a sequence of signals representing the computer program forperforming one of the methods described herein. The data stream or thesequence of signals may for example be configured to be transferred viaa data communication connection, for example via the Internet.

A further embodiment comprises a processing means, for example acomputer, or a programmable logic device, configured to or adapted toperform one of the methods described herein.

A further embodiment comprises a computer having installed thereon thecomputer program for performing one of the methods described herein.

A further embodiment according to the invention comprises an apparatusor a system configured to transfer (for example, electronically oroptically) a computer program for performing one of the methodsdescribed herein to a receiver. The receiver may, for example, be acomputer, a mobile device, a memory device or the like. The apparatus orsystem may, for example, comprise a file server for transferring thecomputer program to the receiver.

In some embodiments, a programmable logic device (for example a fieldprogrammable gate array) may be used to perform some or all of thefunctionalities of the methods described herein. In some embodiments, afield programmable gate array may cooperate with a microprocessor inorder to perform one of the methods described herein. Generally, themethods are performed by any hardware apparatus.

The apparatus described herein may be implemented using a hardwareapparatus, or using a computer, or using a combination of a hardwareapparatus and a computer.

The apparatus described herein, or any components of the apparatusdescribed herein, may be implemented at least partially in hardwareand/or in software.

The methods described herein may be performed using a hardwareapparatus, or using a computer, or using a combination of a hardwareapparatus and a computer.

The methods described herein, or any components of the apparatusdescribed herein, may be performed at least partially by hardware and/orby software.

While this invention has been described in terms of several embodiments,there are alterations, permutations, and equivalents which fall withinthe scope of this invention. It should also be noted that there are manyalternative ways of implementing the methods and compositions of thepresent invention. It is therefore intended that the following appendedclaims be interpreted as including all such alterations, permutationsand equivalents as fall within the true spirit and scope of the presentinvention.

LIST OF ACRONYMS AND SYMBOLS

eNB Evolved Node B (3G base station) LTE Long-Term Evolution UE UserEquipment (User Terminal) like wearables, low- power nodes (e.g. NB-IoTdevices) or any type of IoT device RSU Road Side Unit Uu eNB-UE link PC5UE-UE link D2D Device-to-Device IE Information Element V2VVehicular-to-vehicular communications V2X Vehicular-to-everythingcommunications SL Sidelink HARQ Hybrid-ARQ PSCCH Physical SidelinkControl Channel PSSCH Physical Sidelink Shared Channel TB TransportBlock RI Rank Indicator PMI Precoder Matrix Indicator CQI ChannelQuality Indicator ARQ Automatic Repeat Request RSSI Received SignalStrength Indicator ACK Acknowledgement Packet NACK Non-ACK (see above)CRC Cyclic Redundancy Check MCS Modulation and Coding Schema LBTListen-before-Talk CSMA/CA Carrier Sense Multiple Access with CollisionAvoidance IoT Internet of Things

REFERENCES

[1] Lenovo-Motorola Mobility, Sidelink feedback information, 3GPPTechnical Document- R1-1707773, Hangzhou-P.R. China, May 2017. [2]Huawei, Sidelink link adaptation with feedback information for FeD2D,3GPP Technical Document- R1-1707041, Hangzhou-P.R. China, May 2017. [3]ZTE, Discussion on FeD2D Feedback scheme, 3GPP Technical Document- R1-1707210, Hangzhou-P.R. China, May 2017. [4] Intel, Sidelink FeedbackInformation and Signalling for Wearable and IoT Use Cases, 3GPPTechnical Document- R1-1707335, Hangzhou-P.R. China, May 2017. [5] LGElectronics, Discussion on feedback information on sidelink, 3GPPTechnical Document- R1-1707586, Hangzhou-P.R. China, May 2017. [6] Sony,Discussion on sidelink adaptation and feedback information, 3GPPTechnical Document- R1-1708265, Hangzhou-P.R. China, May 2017. [7] J.Schlienz and A. Roessler, Device to Device Communication in LTE,Whitepaper, Rohde-Schwarz, pp. 1-36. [8] Chairman's Notes, RAN1#88bis.[9] E. Dahlman, S. Parkvall and J. Skold, “4G LTE- Advanced Pro and theRoad to 5G”, Elsevier, 3^(rd) Edition, 2016. [10]  3GPP, “Physical LayerMeasurements”, TS 36.214 v. 14.2.0, Apr. 2017.

1. A communication device, wherein the communication device isconfigured to receive one or more information units from a plurality ofother communication devices, wherein the communication device isconfigured to receive a resource allocation message from a managingcommunication device, wherein the resource allocation message defines anallocation of bit positions associated with an acknowledgement ofinformation units received from the plurality of other communicationdevices in a combined acknowledgement information unit; and wherein thecommunication device is configured to transmit a combinedacknowledgement information unit in response to a reception ofinformation units from a plurality of other communication devices usingthe allocation of bit positions defined in the resource allocationmessage.
 2. The communication device according to claim 1, wherein thecommunication device is configured to broadcast or multicast thecombined acknowledgement information unit.
 3. The communication deviceaccording to claim 2, wherein the communication device is configured tobroadcast the combined acknowledgement information unit to the othercommunication devices via a side link which does not involve a basestation.
 4. The communication device according to claim 1, wherein thecommunication device is configured to set bits at bit positionsassociated with one or more other communication devices from which oneor more information units were properly received to a first bit valueand to set bits at bit positions associated with one or more othercommunication devices from which one or more information units were notproperly received or from which no information units were received to asecond bit value which is different from the first bit value.
 5. Thecommunication device according to claim 1, wherein the communicationdevice is configured to transmit a combined acknowledgement informationunit for information units received from different other communicationdevices within a predetermined period of time.
 6. The communicationdevice according to claim 1, wherein the resource allocation messagealso defines in which wireless resource unit the combinedacknowledgement information unit is to be transmitted, and wherein thecommunication device is configured to transmit the combinedacknowledgement information unit in the wireless resource unit specifiedby the resource allocation message.
 7. The communication deviceaccording to claim 1, wherein the communication device is configured toevaluate a resource allocation message which is piggybacked on data. 8.A method for communication, wherein the method comprises receiving, at acommunication device, one or more information units from a plurality ofother communication devices, receiving a resource allocation messagefrom a managing communication device, wherein the resource allocationmessage defines an allocation of bit positions associated with anacknowledgement of information units received from the plurality ofother communication devices in a combined acknowledgement informationunit; and transmitting a combined acknowledgement information unit inresponse to a reception of information units from a plurality of othercommunication using the allocation of bit positions defined in theresource allocation message.
 9. A non-transitory digital storage mediumhaving a computer program stored thereon to perform the method forcommunication, wherein the method comprises receiving, at acommunication device, one or more information units from a plurality ofother communication devices, receiving a resource allocation messagefrom a managing communication device, wherein the resource allocationmessage defines an allocation of bit positions associated with anacknowledgement of information units received from the plurality ofother communication devices in a combined acknowledgement informationunit; and transmitting a combined acknowledgement information unit inresponse to a reception of information units from a plurality of othercommunication using the allocation of bit positions defined in theresource allocation message, when said computer program is run by acomputer.